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Examining VSEPR though the Cross Cutting Concept of Patterns

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student whiteboard about VSEPR before the lesson

Last year, I taught Valence Shell Electron Pair Repulsion (VSEPR) theory and then had the students complete the pHET simulation called Molecule Shapes. This year in effort to align to NGSS, I told the students we were going to look at the data available from the real molecules on the simulation and specifically look for patterns which is a cross-cutting concept; one of the three dimensions of the standards. The cross-cutting concept provides a lens for thinking about concepts in science.

Students had to look at the data and determine a pattern. Typically, I have taught VSEPR  and then had the students complete the simulation as a confirmatory activity to the information covered. Here, students started the topic by creating ideas for molecular shapes and an initial rationale. I initially thought all the students would create a similar claim, but was shocked at the variety that arose. It changed the focus of the lesson where no one complained about the shapes or angles, but were curious about making new shapes and seeing if they could debunk a fellow classmates initial claim. The following are a sample of boards that students generated about their patterns as well as a claim to explain how bond shape is determined to be the same.

 

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   Figure 1 - Whiteboard #1

 

One group claimed that for molecules with no lone pairs, the bond angle is equal to three-hundred and sixty divided by the number of bond groups and that if the molecule has lone pairs the bond angle will decrease. If a molecule has no lone pairs, the molecule and electron geometry are different. See figure 1.

 

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   Figure 2 - Whiteboard #2

 

A second group claimed if you increase the number of groups that are bonded and decrease the number of lone pairs of electrons surrounding the given molecule then you will increase the bond angle. See figure 2.

Another group claimed that as the number of lone pairs increases the bond angle decreases. See figure 3.

 

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   Figure 3 - Whiteboard #3

 

Following the board creation students presented their model and students had the opportunity to ask questions and change their initial model. After this, students completed a POGIL activity* on molecular shapes and then re-visited their boards. The POGIL activity helped explain the reasoning behind their claims so students were able to go back and fix their reasoning.

The two activities were sufficient for students to understand VSEPR without direct lecture and provided the students the lens of patterns to think about the topic. I felt the students were more curious to understand the reasoning behind the bond angles and shapes than in previous years.

*The POGIL acivity mentioned above is called "Molecular Geometry". It is just one of the activities available in POGIL Activities for High School Chemistry, Trout, L. ed. Batavia, IL: Flinn Scientific, 2012. 


Mg Lab - A lab(s) that is great for differentiation.

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Mg Lab

What are we doing to help kids achieve?

It is always helpful to have a lab that can be adapted to meet the needs of students. The "Magnesium Lab" is one of these experiments.

This lab can be adapted a number of ways. It can also be "tweaked" to meet the needs of the number of students or time constraints. Here is the "jist" of the lab. Students obtain a small piece of magnesium. They pour a small amount of a strong acid, usually 6 molar HCl, into the bottom of a eudiometer or gas collection tube. They slowly fill the tube with water until it is completely full. The magnesium is placed in the tube with a stopper with holes (sometimes held in place with copper wire). The eudiometer is carefully turned upside down and placed into a tub of water without letting air enter the eudiometer. The acid goes down the eudiometer and reacts with the magnesium metal. Hydrogen bubbles up and it forces the water out the bottom. Students then can record the volume of gas. Michael Morgan discussed a version of this lab, Molar Volume of a Gas Lab that includes a great tip and a handout with instructions. There are many versions of this lab that can be found online or in old lab books. If you have never tried this before, you might want to consider one of the versions outlined below.

Calculating "R".

Students record the volume of hydrogen gas in the eudiometer. Students then record the atmospheric pressure and take into account the pressure due to water vapor. The mass of the magnesium can be converted to moles. The temperature of the water is recorded. It is assumed that the temperature of the gas is the same as the temperature of the water. Students use the ideal gas law to calculate the universal gas constant R and then compare to the actual value.

Calculating Moles

Students do the same experiment as described. They record the pressure, volume and temperature of the gas in the experiment. Students use the combined gas law to find the volume of the hydrogen at standard temperature and pressure. According to Avogadro, and gas at STP should equate to 22.4 Liters of volume for every mole of gas. Students then examine the volume they have and the moles of gas and compare.

Predicting the Volume of Gas

An AP teacher in Ohio came up with this idea that I did this week. Students were getting close to the end of the quarter and finals were approaching. Everybody was tired (including me). We had done some problems with gas laws, the ideal gas laws and Dalton's law of partial pressures. Students were told that they would be provided a piece of magnesium. They had to do the above experiment. Before they began, they had to predict the volume of gas that would evolve. Their grade depended on two parts. First they had to show their reasoning and calculations on a piece of paper. Second they had to predict the volume of gas. The closer the prediction, the higher their grade. See figure 1. Every lab group had a different mass of magnesium. Most groups solved the problem using the ideal gas law and subtracting the pressure of water vapor. The best part of the lab is that they received feedback within ten minutes of starting the reaction.  The part about this lab that I liked the most is that students experienced a great deal of success and that it was easy to grade. Another aspect about this lab that was helpful was the number of concepts students had to use that were great review with exams around the corner. They had to predict products and balance equations. They also had to measure, use significant numbers, record data and work with gas laws. It also involved stoichiometry.

 

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Figure 1 - Doug Ragan replied to my tweet about this lab activity with a grading tool.

 

Do you have a different way to do this lab? Do you have a great lab practical or demonstration that you use? Please consider posting or commenting. We would love to hear from you.

 

Safety: 

Review Lab - Better than a Worksheet

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Micro Titration

"What are we doing to help kids achieve?"

A friend that I work with teaches chemistry in a school within a school. She was trying to find a lab to help students review at the end of the semester. After a little brainstorming together we decided to use an idea from Bob Worley. Last May, I wrote a blog about a titration lab. Bob had posted a comment and proposed an idea that really stuck in my head. He suggested that instead of doing a formal acid base titration, why not do it through mass instead of volume? See the video below. Apparantly, back in the day, scientists believed that once instrumentation improved, gravimetric titrations would provide better results. Since scales were not that great at the time they turned to using volumes for analysis. Using volumes works well, but why not give gravimetric analysis a try? Maybe we could also turn this into a great review of the semester content.

 

 

The Set Up

I started by standardizing a sodium hydroxide solution of about 0.15 M with KHP.  I then used the standardized sodium hydroxide solution to standardize two solutions of HCl. The two acidic solutions were about 0.20 and 0.10 M. I made 250 mL of each solution. I estimated that students could run multiple trials of titrations with these solution and I would have enough for about the next 5 years of class. Next, I made the "stand" for the berel pipette. I bought some really cheap plastic cardboard that is used for yard and election signs. I made a rectangle with a small open area in the bottom middle. I cut two slits in the rectangle and took another approximately two inch by twenty four inch piece that I bent and placed each end in the slits. This created a tripod type of stand (see figure 1). Above the cut out in the rectangle I poked some holes for plactic zip ties. I was able to slide the pipette into the ties. I also ordered some inexpenive "Hoffman clamps" to place on the fat end of the pipette (see figure 2). These clamps allow a student to carefully dial in the drops. The end of the pipette was pulled tight and then cut off. This made the drops much smaller. The smaller ends and the "Hoffman clamps" allows for students to carefully dial in extremely small amounts of liquid. 

 

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Figure 1 - Gravimetric titration set up

 

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Figure 2 - Hoffman clamp on pipette bulb.

 

The Process 

Students were instructed to obtain a small vial and put in a few drops of phenolpthalein. They were to find the mass of the vial and its contents. They then had to fill the vial about one third full with one of the two acids and record the new mass. Students then obtained the base. They filled the pipette with the special tip with the basic solution. They placed the pipette in the apparatus, added the Hoffman clamp and carefully added base to the acid until they saw the first permanant change of color. They recorded the mass of the vial and repeated the procedure for a second trial. Watch the video below to see exactly how the lab is set up.

 

 

The Analysis

There are many ways teachers can direct students to analyze the data from this activity and use it to review the material covered over the entire semester. Here are some questions that a teacher could ask.

Nomenclature - What are the formulas for the reactants and products?

Reactions - Given the reactants, predict the products and write the correct balanced equation for reaction.

Significant Figures Given the masses recorded for the empty and filled vial, what is the mass of fluid added with the correct number of significant figures?

Density - Given the density of the acid and base solutions their recorded masses, solve for the volume of each.

Moles - Find the molar mass of KHP. If you have the grams of KHP and the molar mass of KHP, how many moles of KHP were used when the teacher standardized the base?

Molarity - The molar ratio of KHP to base was 1:1. Given moles of KHP and now the moles of base along with the volume of base, what is the molarity of the base?

Stoichiometry - How many moles of acid were required to react with the base? What is the molarity of the acid? How many grams of the other product should form?

 

I am sure you could come up with more questions. This could be used as a review activity, formative assessment or possibly even a lab practical. There are many possibilities. 


Special Thanks - I want to note again that the set up for this was inspired by Bob Worley.

 

 

Safety: 

Career Profile: Agricultural Chemical Laboratory Supervisor - Jason Kong

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LECO instrumentation in the laboratory

What do bags of dog food, maple syrup, urine from steers and apple cider all have in common with each other? If you answered, “They’re all regulated by Ohio Department of Agriculture (ODA),” you would be correct. If you answered, “They’re all samples that enter your laboratory,” you’d be even more correct!

In the world of agribusiness, the analytical chemist is the veritable soothsayer – answering questions such as, “How do I know what I’m paying for?”, “Is this safe to eat?”, or “How can I know the nutritional value of my homemade pet treats?”. Our job is to ensure sellers are truthful in their claims and that the products we test are free from contaminants. When the state finds an issue, our laboratory results give regulatory agencies the information necessary to take immediate action that protects people, animals, plants and public health.

 

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Figure 1 - The Consumer Protection Laboratory

 

Describe your present position.

As a chemical laboratory supervisor I oversee the operations of our analytical chemistry laboratory. Our laboratory is tasked with testing animal feeds for nutritional content and contaminants, fertilizers and liming materials for economic fraud, various food products for all types of adulteration, and verifying that participants in livestock exhibition competitions aren’t introducing illegal substances into their animals for a competitive advantage.

Did you get to your present position because of your background in chemistry and area of specialization or did life experience(s) take you there?

A little bit of both! Growing up I’ve enjoyed many fields of study from the performing arts to the physical sciences and have always found chemistry to be a little niche that I kept returning to time and time again. From there I majored in Chemistry at the University of California, Berkeley and after getting my B.S. in 2005 proceeded to earn an M.S. at Cornell University in Ithaca, NY in 2008.

I began my job search when the economy took a hit and was grateful to find a position as an analytical chemist for the Office of Indiana State Chemist working on regulating pesticide formulation products and addressing pesticide misuse cases. It was there I learned about the incredible role chemistry plays in the world of agriculture and since then I have not looked back! Having left Indiana in 2013 to pursue my current position, I remain grateful for the opportunity to lead the General Chemistry Section here at ODA.

 

In the world of agribusiness, the analytical chemist is the veritable soothsayer – answering questions such as, “How do I know what I’m paying for?”, “Is this safe to eat?”, or “How can I know the nutritional value of my homemade pet treats?”

 

In what areas of chemistry did you specialize?

I’m a jack-of-all-trades type of chemist. As an undergraduate I spent all my free time doing research as a synthetic inorganic chemist in Jeff Long’s lab, working with and characterizing transition metals for the purposes of designing single-molecule magnets. Once I arrived in graduate school, I shifted my focus to physical chemistry with Peng Chen, working on understanding the kinetics of single-nanoparticle catalysis and utilizing biophysical methods pioneered by the likes of Sunney Xie among others. Having this background of both synthetic and physical chemistry allowed me to thrive in the field of analytical chemistry. When I started my first job in Indiana in 2008, I had forgotten how much I enjoyed my analytical chemistry classes as an undergraduate! My knowledge of synthesis helped me to dive right into modern sample preparation techniques such as QuECHERS, solid phase extraction, opening aerosol containers without losing any propellant, and more. Here at ODA, so much of our work still involves laboratory techniques you may have been exposed to in your introductory chemistry class. Some of the methods employed were designed in the 1950s and are still considered the “gold standard” by many analytical scientists today. I enjoy devoting time at work teaching my team about the chemistry behind various analytical techniques and why they’re considered today’s industry standard.

The other side of the analytical world is instrumentation. How I love instrumentation! My knowledge and familiarity of physical chemistry helped me to quickly understand the principles of chromatography, mass spectrometry, inductively-coupled plasma spectroscopy, combustion analysis, and more. I became very skilled at working with various instruments with my own hands and was able to troubleshoot instruments based on principles employed from my graduate school days. Here at ODA, I devote a significant portion of my time teaching and training my team on how to operate, maintain and repair instruments.

 

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Figure 2 -Inside the laboratory

 

Do you use chemistry daily? Describe what you do on a day-to-day basis.

Absolutely! I divide my day over helping my team prioritize testing schedules, troubleshooting instrumentation, assessing results and verifying them before reporting them out to our regulatory partners. I spend a portion of each day looking at potential innovations in the field looking through various analytical chemistry journals for new methods. I help my analysts design experiments for method development and validation. I speak with state and federal regulatory agencies as a subject matter expert and help them to understand chemistry in layman’s terms. I field phone calls from private citizens needing help with their pet treats. I speak and work with vendors to test their product’s claims in a real-world laboratory setting. I welcome high school and college interns on a regular basis and help them find their way in the laboratory.

On a less-frequent basis, I travel to conferences around the nation to network with other scientists, initiate collaborations and represent the interests of ODA. I use the opportunity to learn about the latest technologies offered as well as the latest needs from the agriculture or food world. I’ve assisted as a judge for the Ohio State Science Day. I’ve worked with our legal team to prepare for court cases. I’ve revived a professional organization from the dead and became its founding president. As a result of that, I’ve hosted professional conferences for the analytical sciences right here on ODA’s campus.

 

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Figure 3 - LECO FP-528 Combustion Analyzer

 

Describe the personal skills that have played an essential role in your present position.

Being a thespian has its advantages! Throughout my time in high school and college I remained active in theater and dance, as an actor, performer, director, and writer. My experience in the performing arts helped me understand how to not merely convey information but also my passion for the subject in an understandable, engaging way. I want my love of the sciences to be infectious. When I teach my staff about how to repair a binary pump, when I am standing in front of a hundred scientists delivering a talk, when I need to explain to policy makers why a specific rule needs to be implemented, or when I speak on the phone with a concerned citizen about their cat food - I make sure every part of my body language is telling the same story. I want to make sure people know that I care, not just about the science, but about them. I want them to know my decisions are made with them in mind.

In addition to performing well, I’ve also learned the importance of listening to your staff and the needs of your customers. When there are thousands of tests that could be performed, how do you know which tests are the most important? How do you know if your team has the capability and capacity to handle adding on additional tests? How do you make sure that the needs of your customers and of the director of the agency are being met? Just as I continue to learn to speak in a way that non-scientists can understand, I also have learned to listen and determine what it is that my clients really need.

What advice do you have for those who wish to pursue this or some other nontraditional career path?

The world of chemistry is open to all kinds of possibilities! Going into college and graduate school, few people ever told me about opportunities in chemistry outside of the pharmaceutical world, the petroleum world or the academic world. Since working this job, my exposure to the hundreds of different avenues of work have simply blown me away. Chemists are involved in nearly every field of work, and it’s so easy to not realize that until much later in life.

 

For further information about a career in agricultural chemistry:

Agriculture and Food Chemistry - American Chemical Society accessed (12/21/18).

Chemists in the Real World - American Chemical Society, Chemist Profiles: Agricultural and Food Chemistry (accessed 12/21/18).

What Do Chemists Do Video Series, American Chemical Society (accessed 12/21/18).

AOAC INTERNATIONAL - An important resource for analytical chemists.

Journal of AOAC International - A journal for members of AOAC.


Editor's Note: Faces of Chemistry - Career Profiles is a project intended to help teachers and their students understand the wide variety of career paths available in the field of chemistry. If you know a professional in a chemistry related field that would be interested in authoring their own career profile or if you have a specific career you would like us to highlight, please reach out to us using our contact form

Faces of Chemistry - Career Profiles

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“The Many Faces of Chemistry”1 was the theme of National Chemistry Week in 2007. Journal of Chemical Education (JCE) staff, including precollege editors Erica Jacobsen and Laura Slocum, invited a diverse group of 13 professionals 2-14 working in chemistry related fields to write about their background, experience and advice they had for those interested in a similar career path. 

 

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Figure 1– Three of the authors from the Faces of Chemistry Profiles 2007. 1

 

Those 13 articles from 2007, provided chemistry instructors a resource to help students glimpse the variety of chemistry related fields open to them. ChemEd X is following up on the 2007 project to provide teachers and students with profiles that reflect not only the growing diversity of chemistry related careers, but also the increasing diversity of people working in those positions. We hope that every student will be able to see a face that looks similar to who they see in their own mirror every day.

 

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Figure 2– Questions provided to the authors.

 

We will use the same questions that JCE staff compiled for the 2007 project, but our platform will allow the authors flexibility in their presentation. Authors may choose to format their profile like those from JCE, but some may choose to create a slideshow, video or podcast instead. This is an ongoing project intended to help teachers and their students understand the wide variety of career paths available in the field of chemistry. If you know a professional in a chemistry related field that would be interested in authoring their own career profile or if you have a specific career you would like us to highlight, please reach out to us using our contact form


ChemEd X - Faces of Chemistry 2019

Kong, Jason, Career Profile: Chemical Laboratory Supervisor, Jason Kong, 12/22/18. 

Coming soon...Noel, Nakita, Career Profile: Postdoctoral Research Fellow, Dr. Nakita K. Noel 

Interested in even more information about chemistry related careers? The American Chemical Society offers a wealth of information related to chemistry careers on their website. You can find career profiles, a video series about what chemists doadvice on how students can make a plan toward a career in chemistry and more.


Journal of Chemical Education - The Many Faces of Chemistry 2007

1 – Thirteen Career Profiles, JCE staff, Journal of Chemical Education, 2007, 84 (10), 1562 - https://pubs.acs.org/doi/pdf/10.1021/ed084p1562 (accessed 8/18/18)

2 -Dudareva, Natalia, Career Profile: Biochemist and Plant Molecular Biologist,Journal of Chemical Education, 2007 84 (10) 1564 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1564 (accessed 8/18/18)

3 - Ehrlich, Alan, Career Profile: Patent Attorney, Journal of Chemical Education,2007 84 (10) 1583 - https://pubs.acs.org/doi/pdf/10.1021/ed084p1583 (accessed 8/18/18)

4 - Hanna, Raven, Career Profile: Molecular Biophysicist Turned Jewelry Designer,Journal of Chemical Education, 2007 84 (10) 1581 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1581 (accessed 8/18/18)

5 - Jemison, Mae, Career Profile: Biomedical Engineer, Journal of Chemical Education,2007 84 (10) 1569 - https://pubs.acs.org/doi/pdf/10.1021/ed084p1569 (accessed 8/18/18)

6 - Kauns, J. Douglas, Career Profile: FBI Special Agent, Journal of Chemical Education, 2007 84 (10) 1575 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1575 (accessed 8/18/18)

7 - Maynard, Jim, Career Profile: Lecture Demonstrator, Journal of Chemical Education, 2007 84 (10) 1578 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1578 (accessed 8/18/18)

8 - Parker, David, Career Profile: Fire Department Hazardous Materials Administrator, Journal of Chemical Education, 2007 84 (10) 1576 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1576 (accessed 8/18/18)

9 - Rodriguez, Eloy, Career Profile: Natural Products Chemist, Journal of Chemical Education, 2007 84 (10) 1582 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1582 (accessed 8/18/18)

10 - Sweetman, Amy, Career Profile: Biological Psychologist and Artist, Journal of Chemical Education, 2007 84 (10) 1567 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1567 (accessed 8/18/18)

11 - Wollowitz, Sue, Career Profile: Pharmaceutical Chemist, Journal of Chemical Education, 2007 84 (10), 1585 - https://pubs.acs.org/doi/pdf/10.1021/ed084p1585(accessed 8/18/18)

12 - Wood-Black, Frankie, Wright, Stephen, Career Profile: Environmental Chemist,Journal of Chemical Education, 2007 84 (10), p 1574 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1574 (accessed 8/18/18)

13 - Wright, Stephen, Career Profile: Medicinal Chemist, Journal of Chemical Education, 2007 84 (10), p 1579 -https://pubs.acs.org/doi/pdf/10.1021/ed084p1579 (accessed 8/18/18)

14 - Young, Jay A., Career Profile: Safety Consultant, Journal of Chemical Education,2007 84 (10), p 1572 - https://pubs.acs.org/doi/pdf/10.1021/ed084p1572(accessed 8/18/18)

Synergistic Inquiry

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Synergistic Inquiry

Inquiry learning (also known as discovery learning)1 is an educational method that “places responsibility on the students to pose hypotheses, design experiments, make predictions…decide how to analyze results…and so on”.2 Several authors have attempted to define and describe the characteristics of inquiry learning in the science classroom.3,4

It is commonly assumed that higher levels of inquiry are achieved as student control over the experimental process increases. For example, Buck, Bretz, and Towns have categorized inquiry-based lessons by the level of autonomy that students experience as they carry out investigations (Table 1).3 According to these authors, the level of inquiry attained in lessons can be determined by deciding if it is the student or teacher that poses questions, uncovers relevant theory and concepts, develops procedures, analyzes and communicates results, and draws conclusions (Table 1).

 

Table 1: Levels of Inquiry Characterized by Buck, Bretz, and Towns.3

Types of Inquiry Learning

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Types of Inquiry Learning

 

Evidence suggests that inquiry-based learning provides many benefits to students, including increased motivation, learning outcomes, and appreciation of science.1-4 It is argued that students learn how to “do science”2 by participating in inquiry-based activities. It is therefore no surprise that many educators argue that students should be pushed to engage in higher levels of inquiry as much as possible. Indeed, (as noted by Cooper)5 the Science and Engineering Practices (Table 2) of the Next Generation Science Standards (NGSS)6 are essentially the same as characteristics of inquiry outlined by Buck, Bretz, and Towns.

 

Table 2: NGSS Science and Engineering Practices and Associated Characteristics of Inquiry delineated by Buck, Bretz, and Towns.

NGSS Practice

Characteristic of Inquiry Learning or Related to this NGSS Practice

Asking questions and defining problems

Problem/Question

Developing and using models

Theory/Background

Planning and carrying out investigations

Procedures/Design

Analyzing and interpreting data

Results Analysis

Using mathematics and computational thinking

Results Analysis

Obtaining, evaluating, and communicating information

Results Communication

Constructing explanations and designing solutions

Conclusions

Engaging in argument from evidence

Conclusions

 

It is important to note that many authors – including those who champion the practice of inquiry learning – point out exposing students to “higher levels” of inquiry can be counterproductive.1,7-9 For example, ample research shows that students given complete freedom over all aspects of the learning process (similar to authentic inquiry, Table 1) ultimately learn very little.9 On the other hand, inquiry-based approaches in which the teachers provide support (similar to structured, guided, or open inquiry, Table 1) appear to lead to the greatest gains in learning.9 Therefore, students need a great deal of support as they progress towards higher levels of inquiry learning.7-9

 

Synergistic Inquiry

I often use inquiry learning in my classes,and when doing so I attempt to guide my students towards increased independence as they conduct their experiments. However, consistent with the concerns outlined in the previous paragraph, I have begun to wonder if it is always beneficial to push students toward greater autonomy as they carry out scientific explorations. Therefore, I have begun to explore an approach wherein I work alongside my students as they carry out inquiry-based experiences that call upon the science and engineering practices (Table 2). Thus, my students and I work together to solve problems in an approach I call synergistic inquiry. Simply put, synergistic inquiry occurs when students and teachers cooperate in an attempt to answer questions. In the science classroom, this means the student and teacher work together to pose questions and attempt to answer them. I want to be clear: I am not suggesting that synergistic inquiry is a new educational method. Science teachers have been informally using this approach for a very long time. Rather, in this article I intend to describe and characterize synergistic inquiry as a valid educational tool, to contextualize it within the scope of inquiry-based methods, to propose its use as a way to prepare students for (and engage students in) valuable inquiry learning, and to provide helpful tips to teachers who wish to implement synergistic inquiry in their classrooms.

Synergistic inquiry changes the emphasis from having students “do science” to experiencing the process that people undergo when they train to become scientists. The focus is not so much on having students carry out all of the characteristics of inquiry on their own, without the input of the teacher, but rather using all the characteristics of inquiry – along with their teacher – to attempt to answer questions. Table 3 (below) indicates that synergistic inquiry contains all the characteristics of inquiry, but that the student and teacher cooperate in carrying out these tasks.

The process of synergistic inquiry is carried out during the training of scientists. For example, when I was training to be a professional chemist, I worked under the tutelage of advisors who were experts in their area of study. My advisors helped me to learn the theory required to understand and analyze experiments within the field. They taught me how to conduct various experiments, to ask relevant questions, and to design and implement experiments intended to answer those questions. They helped me analyze results and to draw conclusions from those results. As I gained confidence and a bit of expertise in the lab, I moved from being a “student” of my advisors to a colleague that worked alongside them with the common goal of solving various problems. It was only after several years of working with these experts that I was able to formulate questions and design experiments independently. The point of relating this experience of mine is to stress that I didn’t learn to become an independent researcher – or to “do” science –by making certain that I independently worked on problems, designed experiments, analyzed results, and proposed conclusions. Rather, I learned how to do independent research by working alongside those who were doing independent research. In this vein, I have found that many of my students in my classes capture a glimpse of how the scientific process plays out by working alongside me and with their own classmates as together we attempt to use chemistry to gain insight into the workings of various phenomena.

 

Table 3: In Synergistic Inquiry, students, peers, and teachers participate together throughout the experimental process in an attempt to answer questions. This table is a modified version of that presented in Buck, Bretz, and Towns, Journal of Science Teaching (2008).

 

How might synergistic inquiry be implemented in the classroom?

I often require my students to investigate scientific questions as part of regular coursework, setting apart several laboratory periods specifically for exploratory work. These investigations are typically carried out during the latter part of a course. Students are required to give presentations (either poster or oral) to their classmates at the conclusion after the work is completed (see Appendix for a guide I give students to assist in constructing these presentations). I have used this approach in courses that span a wide range of sophistication: science for non-majors, introductory chemistry, general chemistry, analytical chemistry, and physical chemistry.

To begin the process, I ask students to individually meet with me to discuss experimental ideas. Students often have an idea of what they would like to study, but I almost always provide input. Many times I do not know what the outcome of the investigation will be. For example, I once had a student remark that she wished to determine if cooking foods in the microwave oven adversely affected the nutritional content of foods. Given the broad nature of her query, I suggested we try to answer a more specific, but related question. I recommended we determine if heating orange juice in the microwave oven diminished the content of ascorbic acid (Vitamin C) in the juice. Thus, the student and I worked together to frame a question. She provided the impetus for what she wished to study, and I used my expertise to guide her into a chemical problem that could potentially be answered within a reasonable number of laboratory periods. This is a key idea of synergistic inquiry: the instructor acts as a consultant, providing expertise to help students throughout the entire scientific process.

 

Role of the teacher in synergistic inquiry 

Thus, the teacher plays the role of an expert consultant when synergistic inquiry is used in the classroom. Teachers should provide opinions on student-proposed experiments, models, and conclusions. Teachers should point out to students when conclusions display flawed reasoning or misapplication of scientific principles. This does not mean the student should always take the advice of the teacher. In almost all cases, I allow students to carry out proposed experiments that I think won’t work or are otherwise poorly designed. Some of my favorite moments occur when my students demonstrate that I am wrong (yes, this happens). If a student and I disagree on a particular model or conclusion, we try to envision and carry out experiments that – when completed and analyzed – will resolve the disagreement.

I generally find that students need assistance determining how to conduct and monitor experiments in a quantitative manner. I therefore routinely ask students to envision ways to carry out experiments that lead to the creation of graphs: Does varying some measurable parameter cause a change in another measurable phenomenon? The most common variables we manipulate are temperature or concentration of some substance. Sometimes students figure out how to do this on their own, other times I come up with ideas for them. Also, students often need help designing and recognizing the value of control experiments. In the orange juice experiment mentioned earlier we obviously tested the Vitamin C content of orange juice that had – and had not – been microwaved. However, as an additional control we tested the Vitamin C content of a solution of known concentration of ascorbic acid in water. Another good control would have been to measure the Vitamin C content of a sample of orange juice that had been heated on a stove top rather than in the microwave.

Also, students often need to be prompted to carry out multiple trials and to statistically analyze results. For example, in our orange juice experiment, my student reported to me that she found 12.2 mg of Vitamin C in a sample of fresh orange juice, but only 11.9 mg of Vitamin C in a sample of microwaved orange juice. On the basis of these observations she concluded that microwaving removed some of the Vitamin C from the orange juice. I suggested that she run additional trials and compute standard deviations of the results. After running 5 samples each, she found that 12.1 ± 0.5 mg and 12.2 ± 0.3 mg of Vitamin C was present in fresh and microwaved orange juice, respectively. Thus, after running several trials and statistically analyzing the result, her conclusion was that within experimental error, microwaving orange juice does not change its Vitamin C content.

"when scientists are doing their best, they don’t really “want” a desired outcome. Ultimately, what we “want” is to observe, describe, and explain what is really happening."

The teacher also helps students deal with failure. Students often get frustrated when they can’t build a desired project or when an experiment does not achieve an anticipated result. I like to tell my students “I have never had a failed experiment – only new observations”. In essence, failure is not possible. I try to impress upon students that when scientists are doing their best, they don’t really “want” a desired outcome. Ultimately, what we “want” is to observe, describe, and explain what is really happening.Thus, I encourage students to do exactly that: report exactly what they did, exactly what they saw, and try to explain why they got the observed result. I inform students that I will very likely use their observations to try again in the future, and knowing what has already been attempted is extremely helpful in moving forward and designing new experiments. Consistent with this attitude, students are not graded on whether their experiments are “successful” or not. Rather, heavy emphasis is placed on specific and complete reporting of experimental procedures, the presentation of experimental data, and the agreement between the conclusions drawn and the evidence presented.

Ideas for investigations

Coming up with individual experiments for all students is a difficult task. One way to alleviate this problem is to have students work in groups of two or more. Over the years I have found some guidelines that are helpful in dreaming up experiments for students. Simply asking a student what it is that they want to study (again, with my input) sometimes generates fantastic ideas. I have also had students repeat experiments found in the Journal of Chemical Education, posted on ChemEdX, or attempted in previous years by former students. When repeating experiments, we try to figure out ways to tweak or extend what has already been done. Because of this, my students and I have worked on some questions over the course of several years with multiple, different students working on the same general question. Thus, new batches of students build upon the results of past generations of students – much in the same way that the scientific endeavor plays out. I often want to make improvements to demonstrations or laboratory experiments that I use in class. Having students work on these improvements makes for great project ideas. Exploring the interface between chemistry and art or cooking is a favorite of students. For example, I have had students use anthocyanin from cabbage juice at different pH levels as the only colorant for a “painting” or “drawing”. Students have generated some impressive artwork using this idea (Figure 1), but we have yet to figure out how to keep the colors from fading over time (yes, this is another question my students have explored). Finally, finding ways to connect experiments to a student’s career aspirations or favorite sport works well. My favorite example of this was when a student who was a pole vaulter tested the amount of bend his pole experienced at different temperatures. To prepare the pole at different temperatures, he incubated the pole in a rain gutter filled with water at different temperatures.


Drawing colored with anthocyanin pigments

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Drawing colored with anthocyanin pigments

Figure 1:Drawing colored using anthocyanin with cabbage juice at different pH. Artwork by Michael Tebo.

 

"it seems that as I tell the stories of discovery and experimental work from past students, my current students begin to believe that they, too can do real science."

What are some benefits of synergistic inquiry?

Over the years I have noticed that students take a great deal of ownership in their projects, often working double or triple the time I require for in-laboratory work. Students routinely work on experiments outside of normal class time. This implies that experiments involving synergistic inquiry increase student motivation and interest in science. I regularly observe students informally communicating with each other about their experiments. They explain project details to others, brainstorm possible experiments to carry out, and discuss the merits of various explanations for observations. Because I require all students to work on different questions, students become exposed to a wide variety of inquiry-based explorations through their conversations. Furthermore, I often incorporate experiments and results that past students have achieved when presenting various chemical concepts during lecture. By doing this, students are exposed to the thinking involved during inquiry-based experimentation throughout the entire school year. While I have not collected data on this, it seems that as I tell the stories of discovery and experimental work from past students, my current students begin to believe that they, too can do real science.

 

Conclusion

One of the primary goals of teaching is to move students toward greater independence. As a result, we teachers tend to see the various levels of inquiry (Table 1) as a hierarchy, where structured inquiry < guided inquiry < open inquiry < authentic inquiry. It is therefore natural for us to want our students to be in charge of all aspects of exploratory work. However, we must be careful not to give students too much freedom before they are ready: students must learn to walk before they can run. Indeed, research shows that inquiry-based work leads to the most learning gains when students experience a balance of structure and freedom.1,9 Recognizing this, some chemistry teachers have described how to properly prepare students to engage in inquiry in the chemistry classroom.7,8 Building upon this work, I have endeavored herein to describe a process I call synergistic inquiry, in which chemistry teachers guide students in inquiry-based investigations by working with them. Synergistic inquiry frees the teacher from worrying about helping students too much as they approach scientific questions: the teacher and student help each other to solve scientific problems. In this sense, it allows the teacher to help students engage with inquiry-based explorations “at their own pace”. In my experience, some students need a lot of help along every step of the way, while other students need very little assistance. Synergistic inquiry also frees students and teachers from the constraints of worrying about what level of inquiry has been attained, and to instead to just do science. Like all inquiry learning, synergistic inquiry demystifies scientific practices (and the scientific method itself) by inviting students to participate in them. However, it also emulates the process of how people become scientists. In my opinion, the best part of using synergistic inquiry is that it transforms my classroom into a team of human beings who work together to explore the many wonders of the physical world.

 

Acknowledgements

I would like to thank the reviewers of this manuscript for their expertise and helpful suggestions. I would also like to thank the many students I have worked with over the years, who have allowed me to learn, explore, and question so much more than I could by myself.

 

References

1. Kirschner, P.A.; Sweller, J.; Clark, R. E. Educational Psychologist, 2006, 41, 75-86.

2. French, D.; Russell, C. BioScience, 2002, 51, 1036-1180.

3. Buck, L. B.; Bretz, S. L.; Towns, M. H. Journal of College Science Teaching, 2008, 38, 52-58.

4. Fay, M. E.; Grove, N. P.; Towns, M. H.; Bretz, S. L.; Chemistry Education Research and Practice, 2007, 8, 212-219.

5. Cooper, M. M. Journal of Chemical Education, 2013, 90, 679-680.

6. The Next Generation Science Standards https://www.nextgenscience.org/

7. Criswell, B. Journal of Chemical Education,2012, 89, 199-205.

8. Buck, L.B.; Towns, M. H. Journal of Chemical Education,2009, 86, 820-822.

9. Mayer, R. E. American Psychologist, 2004, 59, 14-19.

 

Appendix - Presentation guidelines

 

Panel

 

 

Necessary components

 

Comments

Title

Name of your experiment, Name of author and school affiliation.

Try to make as eye-catching as possible.

Purpose

Explanation of why the project is important or interesting.

Use text large enough to view from 2 meters away.

 

Background / Introduction

Explanation of necessary theory, equations and diagrams required to understand your experiments.

Use text large enough to view from 2 meters away.

Details may be explained orally to interested persons.

Materials and Methods

Explain in detail how you carried out your experiments.

Include enough information so that your experiments can easily be replicated.

 

Data

Graphs, charts, calculations, diagrams, spectra, etc. that present data collected during your experiments.

Use color!  Keep data as visually oriented as possible.  USE ONLY ORIGINAL WORK.

Interpretation

Text and diagrams that explain why you think your data supports your conclusion.

Keep explanations as simple and visual as possible. 

 

Conclusion

Text describing, in a very concise manner, all you have learned as a result of the experiments you conducted.

2 or 3 sentences should suffice.  Keep the text large enough to view from 2 meters away.

 

References

A list of the literature you have read to provide you with the necessary background to complete your work.

At least 2 references are expected.

 

Acknowledgements

A list of the people and institutions that have provided assistance in completing your work.

People love to be thanked.  Do not discount this part of your poster.

 

 

Why I Am Attending ChemEd 2019

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ChemEd 2019 logo

I am already planning for my trip to Illinois in July to attend ChemEd 2019! Let me tell you why I want to attend.

It all began a few years ago. I was complacent in my routines of teaching state level and Advanced Placement Chemistry after only nine years of teaching. A colleague mentioned a program I should apply for in my area that helps to connect STEM teachers. Many regions have networks through which science teachers can share ideas. When I joined a team in my area I was immediately reinvigorated. I met four chemistry teachers on Long Island who were ready and willing to share resources and change the chemistry education world! Four. Just four. We were ambitious and excited but we had no idea where to start! One of my new colleagues was Stephanie O’Brien. (We are now fellow ChemEd X Lead Contributors.) We were researching ideas and when we saw the opportunity to attend conferences, the two of us decided to attend out first ChemEd Conference, the 2015 ChemEd Conference in Kennesaw, Georgia. We were forever changed.

We drove fourteen hours straight to Kennesaw and made it just in time to the opening ceremonies. Exhausted and delirious we listened to some announcements but came back to life when we saw Aaron Sams (of FlippedClass.com fame) during the plenary. Inspired, but still tuckered out, we decided to look ahead to plan which workshops and sessions we should attend for the rest of the week. We opened our programs and were overwhelmed by the amount of options we had. Should we go to the session about AP Chemistry lessons or the workshop for inquiry labs? And then in session two, how do we pick from the three we narrowed it down to? The choice was obvious, divide and conquer! My friend and I split up the sessions and met up at dining times to share our ideas. We couldn’t speak fast enough to get out all the new ideas and exciting things we witnessed. Our tiny notebooks were flooded with diagrams, lab ideas, and scribblings of notes that we needed to keep for the school year. And our school bags were packed with “make and take” activities, handouts from

workshops and symposia, and freebies from the exhibit hall.

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Chemistry instructors at all levels can benefit from this conference. There are numerous workshops and sessions devoted to state level, Advanced Placement and college level classes. There is a daylong symposium at ChemEd devoted specifically to AP chemistry. There is at least one session led by the AP chief reader or someone with similar knowledge that reviews that year’s AP exam and explains how the exam was graded and scores were calculated. They also point out common pitfalls and help teachers understand how they can enhance their methods to help their students avoid those. I got a lot out of that session with the Chief Reader. At the end of his session, they also explained how to become an AP Exam Reader. I promptly introduced myself to the chief reader at the time, applied, and I can now say I have read two exams and it is an amazing experience.

By the end of the conference, we ran 3.1 miles in the Mole Run, participated in a lecture by Ramsey Musallam, won books written by Larry Gonick, witnessed “So You Think You Can Demo?” where Tom Kuntzleman introduced us to orange peel balloon popping, and we attended numerous workshops and symposia. It was only July and our classes didn’t begin until September, but it was not soon enough for us! We were eager to try our new skills. But the best part of the conference was meeting a new network of friends that share a common nerdy passion for all things chemistry. This network of chemistry teachers has kept me enthused all year long, for years on end.

Since my first ChemEd Conference, I have attended each ChemEd and BCCE (Biennial Conference on Chemical Education), which alternate each year. Every summer my network of teachers has grown. I can credit most of my understanding of NGSS, CER (claim, evidence, reasoning), and ADI (argument driven inquiry) to these inspiring teachers that I have grown to admire and respect. Now, we share a constant dialogue of ideas (and sometimes just fun jokes) on Twitter and in our own private text chat.

I cannot wait to attend this year’s ChemEd conference hosted by North Central College in Naperville, IL. The conference runs from July 21st to July 25th. I am super excited to hear from plenary speakers Deborah Blum (writer of “The Poisoners Handbook” and “The Poison Squad”) and Theodore Gray (writer of “The Elements: A Visual Exploration of Every Known Atom in the Universe,” “Molecules: The Elements and the Architecture of Everything,” and other works) because I have read and referenced their books in my chemistry classes. I am also planning to run the 6.02km Mole Run (maybe even reclaim my place as second female finisher), listen to Michael Offutt play his chemistry tunes at the Mole Breakfast, as well as attend excursions to Fermilab and Argonne Lab. But I am the most excited to visit old chemistry friends and make new ones!

So if you feel that can’t connect to like-minded teachers in your area, or have a network that is looking for more inspiration, consider attending ChemEd in Illinois. I invite you to visit me and other ChemEd X contributors at our booth in the exhibit hall, at our ChemEd X Symposium or just out and about as we attend presentations and engage in the social gatherings.

Check out the ChemEd 2019 website and join their mailing list so you don't miss any announcements.

Chemistry ROCKS!

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macroscopic view of table salt

I must admit, I feel somewhat of an imposter in the chemistry world as I have a Master’s degree in geology. While my research was in the field of geochemistry, I (like most geologists) have a deep and abiding love for rocks and minerals. If you walk in my classroom, you will find various rock samples on my desk, a poster of minerals from around the world and of course, boxes full of rocks! I have only taught a geology class once, so I have needed an outlet for all this pent up love for rocks. The great thing about geology is, it's all about chemistry! I want to share one of my favorite links between geology and chemistry that my students think is pretty cool too. 

If you use Modeling Instruction, you might be familiar with the “Crystal Structures” activity using Mercury software. I wrote about my switch from Mercury to MolView on my blog a few years back and Michelle Okroy wrote about the program in her blog post, MolView: An App to View Structural Formulas and Models, as well. This activity allows students to see how different types of compounds vary at the particulate level. I like to extend this activity to show students how microscopic observations impact macroscopic observations. You can show these structures to students as part of a whole class discussion or have your students open MolView and manipulate the structures themselves. Alternatively, you might consider using the Tools tab in MolView to copy the embed code of specific structures and insert them into your own website so students don't need to figure out how to use the website. You can see samples of the interactive structures that can be embedded below (Figures 1B & 2B).

The first example I show is graphite and diamond (see Figure 1).

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Figure 1A - Particle view of graphite (left) and diamond (right)

Figure 1B - Interactive 3D particle view of graphite

 

Graphite works great in pencils because it breaks off in sheets as you write. Diamond is made of the same atoms, but a completely different structure gives it completely different properties. 

The next example is sodium chloride (table salt), also known in the geology world as halite (see Figure 2).

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Figure 2A -Particle view of sodium chloride

Figure 2B - Interactive 3D particle view of sodium chloride

 

Students quickly see that halite has a cubic crystal structure. With a magnifying glass and some table salt, students can see how the microscopic structure extends to the macroscopic structure (see Figure 3). 

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Figure 3 - Macroscopic view of table salt

 

You may already show your students the first examples I have shared. I hope this last one, calcium carbonate, is new to you! It is known in the geology world as calcite (see Figure 4).

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Figure 4 - Particulate view of calcium carbonate

 

Students usually describe the shape of calcite as a slanted rectangle. The geology term is for that shape is rhombic. This is when I get out my sample of optical calcite and use my iPevo camera to show how the rhombic structure of calcite produces double refraction of light that passes through it (see Figure 5).

      

double_refractions.gif

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double refractions

Figure 5 - Sample of optical calcite that shows double refraction of light

 

Students really love seeing the double refraction. What students love even more is when I nonchalantly pull a rock hammer out of my desk and smash a piece of calcite (not my optical sample!) so they can see that not only does calcite grow as a rhomb, it breaks in rhombs as well (see Figure 6). Students are always surprised to learn that the optical calcite was not cut to be that shape.

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Figure 6 - Calcite broken into bits still shows rhombic shape

Most students will never take a geology course so I like to throw in some Earth Science tidbits wherever I can. Calcite makes a reappearance in my acids and bases unit because the field test for determining if a rock contains the mineral calcite is dropping dilute hydrochloric acid on it to see if it fizzes! 

If you are looking for a new way to show your students that chemistry rocks, hopefully geology can give you hand! If you are logged into ChemEd X, you can find directions to help you get started using MolView in the Supporting Information.

Supporting Information: 
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Directions for getting started using MolView

Immobilization of Lactase Enzyme on Alginate Beads - A Quick Test

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milk, lactase, glucose test strips

I came across an interesting Journal of Chemical Education1 article that explains how it is possible to crosslink sodium alginate, leading to the formation of calcium alginate beads. Sodium alginate is commonly used as a thickener in food such as ice cream and fruit-filled snacks.2 It’s a non-toxic and versatile material; not only is it used for food technology purposes but also in drug-delivery and wound dressing systems.

Calcium alginate beads are hydrogels which are a class of cross-linked polymers whose formation is represented in Figure 1: by cross-linking the polymer chains (long lines), we get a network(long lines connected by junctions) that is able to contain plenty of water molecules in its structure.

 

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Figure 1: Schematic representation of cross-linking process

 

The crosslinking process can be achieved either by chemical or physicalmethods, depending on the interaction among the macromolecules of the final network. Chemical hydrogels feature strong interaction in the structure due to the formation of covalent bonds (permanent junctions), whereas in physical hydrogels macromolecules are connected by hydrogen bondings, ionic interactions etc (transient junctions). In any case, either of these types of junctions is able to make the hydrogel insoluble in an aqueous system.3 Biological fluids can be included in the structure as well.

A cool possibility that hydrogels offer, is the immobilization of enzymes in their structure; that is carried out by actually trapping the enzyme in the hydrogel network. In that case, the final result is a heterogeneous catalyst that can be easily separated from reaction mixtures by mechanical methods (such as filtration). Because the enzyme is a catalyst, it is found unchanged at the end of such a procedure. As a result, the hydrogel/enzyme systemcan be used for multiple runs. Therefore, immobilization of enzymes can be economically suitable for industrial applications; in addition, the immobilized enzymes are more stable than the free enzyme and has activity in several denaturing agents.4

I thought it would be cool to immobilize some lactase enzyme onto calcium alginate beads and investigate its ability to hydrolyze lactose. In the digestive system, lactose is normally broken down enzymatically into glucose and galactose (Figure 2) the latter of which can easily be detected by using glucose test strips. These monosaccharides are subsequently metabolized by the body. If lactase enzyme is not produced by the organism, lactose cannot be digested causing diarrhea and intestinal problems. It seems that lactose intolerance is a widespread problem all over the world (here in Italy, over 50% of the population suffers from lactose intolerance).

 

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Figure 2: Hydrolysis of lactose by Lactase enzyme

 

By using glucose test strips the concentration of the monosaccharide can be quickly estimated by looking at the color of the strip after its contact with the processed milk.

 

EQUIPMENT

  • Glucose test strips
  • Lactase enzyme 
  • Milk
  • 2% sodium alginate (2 grams of that slowly added and stirred into 100 ml of water)
  • 1% calcium chloride (1 gram of that mixed into 100 ml of water
  • Plastic pipette (alternatively, a syringe is perfect)
  • 60 disposable syringe, a flexible pipe and a clip

 

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Figure 3: Milk, lactase enzyme and glucose test strips

 

EXPERIMENTAL RESULTS

In this experiment, a physical cross-linking process was conducted. The procedure I followed doesn’t involve the use of any hazardous chemicals.

Calcium alginate beads were obtained following the procedure described in the JChemEd article I cited previously.1 In general, a 2% sodium alginate (2 grams of that slowly added and stirred into 100 ml of water) and a 1% calcium chloride (1 gram of that mixed into 100 ml of water) solution are adequate for conducting the experiment. I’ve been quite lucky to have these chemicals (from Sigma-Aldrich) already available in the lab but you can use any commercial version of them. They are often sold together since they are used in the field of “molecular gastronomy” in order to carry out a process known as Spherification.5 Lactase enzyme and glucose test strips were purchased online (see Figure 3). In some procedures, even an antacid such as Gaviscon® is suggested as a source of sodium alginate.6

Of course, you can use any kind of lactase enzyme supply (I ran a similar experiment in the past and I used a different brand with no qualitative differences in terms of glucose production). In Italy, all these substances, except for Gaviscon®, are not normally available in regular supermarkets; it is very easy to get them online though and I think they are easily found locally in the United States. 

The preparation of the sodium alginate solution is a quite long procedure. To do that, I added 2 grams of sodium alginate powder into 100 ml of distilled water. At least 3 hours of vigorous mixing are required to get a proper solution that results in a dark-yellow kind of color. Once the solution was ready, I added the content of 4 pills (they correspond to 20000 enzyme units) of lactase enzyme to that. Since the pills contain other things along with the enzyme (fillers and excipients), the resulting mixture was quite cloudy. I do think that a commercial lactase enzyme solution would be even better (I would use Lactaid® Enzyme Drops or something like that) but I used the pills because of their minor cost. The mixture was vigorously stirred for 30 minutes; that was added drop by drop (by using either a pipette or a syringe) to a previously prepared calcium chloride solution (prepared by adding 1 gram of CaCl2 in 100 ml of distilled water). The contact between the two substances, immediately gave rise to calcium alginate-lactase beads (Figure 4, left). That procedure allowed to trap and immobilize the enzyme in the beads that became, as said before, a catalytic support the lactose contained in the milk can interact with. When the addition of sodium alginate was completed, I moved to the second step which involved a simple filtration and washing with distilled water of the obtained beads (Figure 4, right). That step was necessary to remove the calcium chloride, fillers/excipients contained in the pills as well as the enzyme that was not trapped in the beads.

 

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Figure 4: From left to right: Calcium alginate beads before and after filtration/washing step

 

The beads were used to pack up a 60 ml syringe (a procedure which reminded me the packing of a chromatography column). See the final set-up in Figure 5.

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Figure 5: Syringe packed with loaded enzyme/calcium alginate beads

 

The procedure I followed afterward was very easy: the milk was poured in the column from the top of that, keeping the clip closed. When all the beads were covered by the milk, I let the system sit for 90 seconds in order to make sure there was a good contact between the beads and the liquid. After that period of time, the milk was drained into a beaker by opening the white clip. The final glucose level was recorded by dipping the glucose test strips in the milk for 60 seconds; after that, the collected milk was poured again into the column and the procedure was repeated. I ran the process three times (see Figure 6 and Table 1 for results).

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Figure 6: Left: Glucose test strips before (Control) and after (Runs) lactose hydrolysis. Right: Relation between colors and glucose levels

 

By looking at the color of the strips, we can say that the glucose levels eventually increased. The color of the Control strip, indicated that there was no glucose in the fresh milk. On the other hand, the colors of the First, Second and Third runs strips are different from the Control one. That means that hydrolyzation of lactose took place as the milk reacted with the beads in the syringe.

 

Table 1: Glucose concentration in the milk depending on the performed run

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I’m quite sure that the final glucose levels can be increased by keeping the milk in contact with the beads for a longer period of time as well as stirring the mixture. Although I was curious to, I didn’t taste the processed milk but I thought it would taste sweeter because of the higher glucose levels (I don’t really suggest you taste the milk either!) Of course, this experiment is just a quick and qualitative evaluation of how lactase can be immobilized and used; in any case, I think it may be a good introduction to enzymes and how they can be used in an industrial kind of setting.

If you’re not interested in completing the immobilization described, just the formation of alginate beads is still a cool demonstration to do.7 Very nice results can be achieved by adding some drops of food dyes into the alginate solution. The reaction with the calcium chloride will give rise to colored beads and a stirring bar would create a nice “colored beads tornado”.7

As usual, I’m open to comments and suggestions about this experiment. I hope you will let me know how it goes if you try it out in your own chemistry lab!

 

ACKNOWLEDGEMENTS

I wish to thank the reviewers of this manuscript for their suggestions and advices.

 

REFERENCES

1. Pignolet, L.H., Waldman, A.S., Schechinger, L., Govindarajoo, G., Nowick, J.S., Labuza, T., The Alginate Demonstration: Polymers, Food Science, and Ion Exchange, Journal of Chemical Education • Vol. 75 No. 11 November 1998, 1430.

2. Dziezak, J. D. Food Technol. 1991, 45(3), 115–132.

3. American Journal of Polymer Science 2014, 4(2): 25-31.

4. React. Funct. Polym. 71: 104-108.

5. Sperification, Wikepedia, https://en.wikipedia.org/wiki/Spherification (accessed 1/6/19).

6. Steven Spangler TV, Gaviscon Worms - Cool Science Experiment, https://www.youtube.com/watch?v=vAbCEYMfM5M (accessed 1/6/19).

7. Chemical Snakes Worksheet, Dynamic Science Website, http://www.dynamicscience.com.au/tester/solutions1/chemistry/chemicaldemos/alginatewksht.htm (accessed 1/6/19).

 

Safety: 

JCE 96.01 January 2019 Issue Highlights

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Journal of Chemical Education January 2019 Cover

Ninety-Six Years New

The January 2019 issue of the Journal of Chemical Education is now available to subscribers. Topics featured in this issue include: chemical biology, innovative curriculum for the classroom and laboratory, promoting effective teaching methods in organic chemistry, improving student conceptual models, cost-effective and low-waste equipment and experiments, using instructional videos to teach, exploring materials science, instrumental analytical experiments, organic chemistry laboratories, research on success in chemistry, from the archives: anodizing.

Editorial

Marcy H. Towns (Purdue University and an associate editor for JCE) invites readers to an international event on February 12, 2019:

Cover: Chemical Biology 

Genetic code expansion (GCE) offers the ability to engineer new protein functions, structures, and interactions using noncanonical amino acids (ncAAs). Despite their utility and foundational roles in recent scientific advances, chemical biology tools like GCE are often left out of undergraduate education. In , Kelsey M. Kean, Kari van Zee, and Ryan A. Mehl present a research-based laboratory course in which students use GCE to study protein structure and function. The cover shows a general overview of GCE machinery required to site-specifically incorporate an ncAA into a model protein, carbonic anhydrase. With many functionally diverse options for ncAAs and sites for incorporation, GCE is a flexible and versatile tool that is well suited for conducting novel research in an undergraduate teaching setting.

Innovative Curriculum for the Classroom and Laboratory

~ Tracy L. McGill, Leah C. Williams, Douglas R. Mulford, Simon B. Blakey, Robert J. Harris, James T. Kindt, David G. Lynn, Patricia A. Marsteller, Frank E. McDonald, and Nichole L. Powell (available to non-subscribers as part of ACS program)

~ Michael K. Seery, Ariana B. Jones, Will Kew, and Thomas Mein

~ Annette W. Neuman and Brenda B. Harmon

~ Nimrat K. Obhi, Ian Mallov, Nadine Borduas-Dedekind, Sophie A. L. Rousseaux, and Andrew P. Dicks

Promoting Effective Teaching Methods in Organic Chemistry 

~ Sarah Beth Wilson and Pratibha Varma-Nelson

~ Jolanda Hermanns and Bernd Schmidt

Improving Student Conceptual Models

~ Leslie Atkins Elliott, Elizabeth Sippola, and Jeffrey Watkins

~ Brian J. Esselman and Stephen B. Block

~ Leyte L. Winfield, Kai McCormack, and Tiana Shaw

~ Meghna A. Manae and Anirban Hazra

~ Rahime Yağmur Ağcalı, Bahar Atik, Ecenaz Bilgen, Berfu Karlı, and Mehmet Fatih Danışman

Cost-Effective and Low-Waste Equipment and Experiments

~ Luis A. Barrera, Alma C. Escobosa, Laila S. Alsaihati, and Juan C. Noveron

~ Taweetham Limpanuparb, Siradanai Kanithasevi, Maytouch Lojanarungsiri, and Puh Pakwilaikiat

~ Nima Noei, Iman Mohammadi Imani, Lee D. Wilson, and Saeid Azizian

~ Alex Schoeddert, Keshwaree Babooram, and Sarah Pelletier

~ Yuguang C. Li, Jeremy L. Hitt, and Thomas E. Mallouk

Using Instructional Videos To Teach

~ Richard A. R. Blackburn, Barbara Villa-Marcos, and Dylan P. Williams

~ Ann H. Kwan, Mehdi Mobli, Horst J. Schirra, Jennifer C. Wilson, and Oliver A. H. Jones

Exploring Materials Science 

~ Alexander J. Boys and Mark C. Walsh

~ Thomas Nagel, Casey Mentzer, and P. Mike Kivistik

~ Mariano Calcabrini and Diego Onna

Instrumental Analytical Experiments

~ Patrick W. Fedick, Robert L. Schrader, Stephen T. Ayrton, Christopher J. Pulliam, and R. Graham Cooks

~ Andrew T. Pemberton, D. Brandon Magers, and Daniel A. King

Organic Chemistry Laboratories

~ Catherine J. Smith, Steven J. Mansfield, Edward A. Anderson, and Jonathan W. Burton

~ Timothy J. Bannin, Partha P. Datta, Elizabeth T. Kiesewetter, and Matthew K. Kiesewetter

~ Carla Grosso, Marta Liber, Amadeu F. Brigas, Teresa M. V. D. Pinho e Melo, and Américo Lemos

~ Irene Dip, Christina Gethers, Tonya Rice, and Thomas S. Straub'

Research on Success in Chemistry 

~ Richard Cohen and Angela M. Kelly

~ Michael Budke, Ilka Parchmann, and Marco Beeken

From the Archives: Anodizing

This issue includes an article on the by Thomas Nagel, Casey Mentzer, and P. Mike Kivistik. The anodizing of other metals has been explored in JCE over the years, including:

~ Emily Gaul

~ George N. Harakas

 ~ Craig J. Donahue and Jennifer A. Exline

~ Anne E. Doeltz, Stanley Tharaud, and William F. Sheehan

~ Rita G. Blatt

Thousands of Reasons to Explore JCE 

JCE is now on its 96th volume, and with well over 1,000 issues of the Journal of Chemical Education to examine, you will always find something useful—including the , and many more, in the . Articles that are edited and published online ahead of print ( are also available.

A “Science Reasoning Rubric” to Support Argumentative Writing

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Components of Reasoning Diagram

It is often said that writing is a window into a person’s thinking. As teachers, we must know what our students are thinking in regards to the concepts we teach. The whole point of the pedagogical approach promoted by the NGSS movement is to help the larger science education community get students thinking more, and more deeply about science content.

I think we should be asking our students to make written or verbal statements in our classes very often. In science class, this type of communication is typically in the form of a claim about what a result means or an explanation about how something works the way it does. In either case, the claim or explanation needs to be supported by thinking that is grounded in facts and logic.

 

The CER Scaffold: Helpful and Hindering at the Same Time

The Claim, Evidence, Reasoning (CER) scaffold has been widely adopted by science teachers. While I think the CER scaffold has provided some much needed help to support writing in science, my students and I have also found it to be confounding. This is because it separates evidence and reasoning from each other when in reality evidence is a critical part of reasoning (for more comments on this, see my previous post ). Evidence is not something that should be considered separate from reasoning since reasoning is really a combination of evidence and additional commentary that attempt to convince others why a claim or explanation is plausible. I prefer to call reasoning an argument. Others call it justification (see by Stephanie O’Brien).

Some writing prompts we give our students are more suited toward claims: “What is the optimal mixture ratio of H2 and O2 to propel a rocket?” Other writing prompts we give are more suited toward explanations: “Why does Kona typically get onshore winds in the late morning and afternoon?” I think an argumentative writing piece consists of two parts, not three parts as suggested by the CER scaffold: 1 - the statement (which is a claim or explanation) and 2 - the argument. Instead of claim, evidence, and reasoning think statement and argument.

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Science Reasoning Rubric

Building upon these thoughts and my revised Components of Scientific Reasoning figure from (see Figure 1), I put together a Science Reasoning Rubric that can be used for many writing prompts in a Chemistry class. It can be used whether a prompt is more suited toward a claim or an explanation (see Figure 2). Together, I think these documents help support students better through the argumentative writing process than CER does. I like that the rubric can be used for lots of the writing tasks students will encounter in a Chemistry class. This means students get used to seeing it, and this consistency is helpful as students write explanations and claims throughout the year.

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What Counts as Evidence?

One question that may come up a lot is, “What counts as evidence?” As shown in Figure 1, evidence can be multi-faceted ranging from core ideas to models to observations or raw data. Before students start a writing prompt, it may sometimes be helpful to guide them toward what could be considered evidence for the task by pointing them toward relevant core ideas, cross-cutting concepts, models, data, etc. This is up to teacher discretion and the art (i.e. challenging part) is to provide this guidance without giving too much away to the students. I shared my own working list of core ideas in a previous Chemed X blog post, .

Another thing I want to note here is that the statement doesn’t necessarily need to come first and then the argument second in a written piece. As shown in Figure 1, the statement and argument should be developed together and in an argumentative piece of writing, it is perfectly acceptable to jump back and forth between comments that establish a claim or explanation and commentary providing reasons it should be believed.

 

Supporting Information: 
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Components of Scientific Reasoning
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Science Reasoning Rubric

Improvisation in the Classroom

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improv text and silhouette of student

I recently attended a workshop at my state conference about improvisation techniques to use in the classroom. As a teacher we are challenged to constantly adapt our pedagogical techniques to meet the needs of our learners, and this workshop provided some new strategies to do just that.

The session was provided by Jessica Mintz and Michael Shanzer who had attended a workshop provided by the through the . The Alan Alda foundation works with scientists and professionals to take their complex knowledge and communicate it with others so it is comprehensible, clear and engaging. The session was great in that it explored new ways of communicating science concepts in a collaborate and creative way.

One of my favorite activities was called “Yes, and…” In this activity the two participants engage in a back and forth through conversation and build off of one another’s idea. The initial prompt at the session I attended was, “I heard that you are applying to NASA to become an astronaut.” The participant had to reply by saying, “ Yes and...and then..." following it up with something on the spot. The two went back and forth for a few minutes. I decided to try this with my students for a recent unit on the periodic table. We first modeled how the improv technique works with the same starter about the astronaut. Students then had conversations with each other back and forth saying “Yes, and....” For the periodic table prompt, students were to pick an element and describe its physical and chemical properties to help the other students identify an unknown element. Below is one sequence of interactions between students.

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It was a nice way to get the students up and interacting with each other, asking each other questions about trends and properties. This activity did come at the end of the periodic table unit so students had learned the key vocabulary and trends to incorporate in the activity. The activity can easily be modified to other topics and was done with a mixed population of special education and general education students. Some of the students were not able to identify elements due to a flaw in the clue provided, which helped them identify a misconception. Sometimes the two students were able to fix the issue by explaining to each other when something didn’t make sense. I like that the students kept it positive, so instead of saying, “No, that doesn’t make sense" if their partner made an error, they kept the conversation moving. For instance one group had this interaction “Yes, and I think higher electronegativity means greater attraction for electrons, not less, is that what you meant?” Or “Yes, and do you know what ionization energy is", or "how can I figure out if it’s higher or lower than another element?”

Another activity explored at the workshop is called the “hard sell”. Two participants had to improv the following situation: you are a door to door hairbrush salesman and have to try selling a hairbrush to a bald man. I couldn’t believe how the participants jumped in on the spot and created a hilarious exchange. I did this with my students just recently for midterm review, where the students had to describe as many possible uses for a particular type of glassware as they could. I was thinking in honor of the international year of the periodic table, I will let my students pick an element and then “sell it to the class” at the end of the year.

An additional activity presented was called the “One Word Story.” In this activity a group of individuals tells a cohesive story one word at a time. It starts when one person says a single word, and unfolds when someone else in the group offers up another word. This can be done by sitting in a circle and going around one person to the next to tell a story. We recently completed a hydrate lab and told a one word story as the report out for the lab. The one word story did not replace the written component of the lab conclusions or report required, but provided a nice closure to the activity. The activity can be adapted to allow students say a few words or a phase for the purpose of time as well as the teacher pointing to random people instead of going in a circle.

In summary, improv in the classroom is fun and engaging and a way to get everyone involved. It is sort of awkward at first, but definitely memorable and the students seem to have fun in the process. If you have any other ideas, please comment below.

Especially JCE: January 2019

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JCE cover for January 2019

The Journal is a jumping-off point. When I read even a finely crafted activity, I know there are going to be tweaks I will need to make to use it. Maybe it’s because of what I do (or don’t) have in my science supply stash. Maybe it’s because my curriculum plan focuses only on a certain concept, so I plan to pull just a piece of the activity. Maybe it’s designed for a different grade level, and I’m adjusting the questions. This customization is one of the reasons I appreciate the “Supporting Info” documents from JCE authors.

Case in point in the January 2019 issue:  (available to JCE subscribers). I like how the lab experiment gives students a better picture of how scientists and engineers work—there is often no “right” answer. The authors describe the activity as “an inquiry-based learning approach where students are presented with a series of possible solutions to a given problem, each with conflicting advantages and disadvantages, requiring students to choose factors they think are most important for a specified application.” Students prepare three mixtures, each with the same amount of Plaster of Paris, but differing amounts of water (cue a discussion of density and viscosity). They place each mixture in identical star-shaped cookies cutter as molds. After adequate drying time, they evaluate various properties, such as strength, aesthetics, and ease of molding.

To bring this into a classroom, I’m set with most of the materials, but the cookie cutters pose a problem. Each small group needs 3 identical star-shaped cutters as molds. Students could test different shapes, depending what I could find at a thrift store or borrow. Or, my cupboards hold options like silicone cupcake molds, jar lids, or silicone candy molds (bacon-shaped, anyone?). The authors also offer suggestions in their article based on teacher testing feedback, such as premeasuring Plaster of Paris for students, so I'll incorporate that. I’d also prefer the middle school groups to estimate the cost of water and plaster using local numbers, rather than those offered by the authors. How to integrate these changes? Look for Supporting Info (see graphic below). After clicking on the link, the article offers four separate files in both PDF and Word formats, making it easy to adjust the details, while retaining the overall lab.

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Chemistry & Coffee Connections

The January 2019 editorial by Marcy H. Towns,  (freely available), shares an opportunity to celebrate the 100th anniversary of the International Union of Pure and Applied Chemistry (IUPAC). The group encourages breakfast get-togethers among women involved in chemistry, at any location around the world. IUPAC’s chosen date—Tuesday, February 12, 2019—is coming fast. You can check for get-togethers in your region, or register your own event at . Get connected!

More from the January 2019 Issue

Mary Saecker reminds readers that JCE is “Ninety-Six Years New” in her post Jump into what’s new and innovative among chemical educators, or visit past valuable pieces. Mary gives you the scoop! 

Is there another article from the Journal that you’ve used as a jumping-off point to fit to your situation? Share! Start by submitting a , explaining you’d like to contribute to the Especially JCE column. Then, put your thoughts together in a blog post. Questions? Contact us using the ChemEd X .

Josh Kenney is Teaching, Youtubing, and Researching Chemistry Education

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photo of Josh Kenney

I think that most people can recall someone whom we considered to be a great teacher. The kind of person who inspired us and motivated us to learn. As I started my career, I remember wondering what kind of teacher my students thought I was. I wondered if I was a great teacher.

Seven years into my career I’ve come to learn that although it’s possible to start out as a “good teacher,” it takes a lot of hard work to become a “great teacher.”

What kind of hard work does it take to become a great teacher? Many books have been written on the subject, and the exact process is debated (e.g. Grossman, 1990). But, research seems to agree that it takes time. Great teachers aren’t “born with it.” Instead, more experience generally results in a more effective teacher (Park & Oliver, 2008). I’m gradually uncovering more about what a great educator looks like, and the steps required to become one. As I learn more, I look forward to sharing what I discover along the way. In my next posts, I’m going to share what I’ve learned about pedagogical content knowledge (PCK) and how we, as chemistry educators, should work to develop this type of knowledge. But first, let me introduce myself.

My name is Josh Kenney. I teach high school chemistry, I create science YouTube videos, and I like to research chemistry teaching and learning.

Teach

I have always asked a lot of “how” and “why” questions, and I studied Chemistry at because it seemed like a subject that provided a lot of answers to my questions. Although I didn’t set out to be a chemistry teacher, an opportunity to lead chemistry study groups and laboratory sections made me increasingly interested in how people acquire knowledge. My passion for chemistry education was born, and I went on to earn a B.Ed at the University of Windsor a year after graduating with my degree in chemistry.

I have been teaching high school chemistry for seven years and have enjoyed innovating within instructional methods like blended learning and project-based learning.

Youtube

In 2013, I started my YouTube channel, . At the time, many of my students spoke English as a second language (ESL), and I had difficulty finding chemistry video tutorials that were short, direct, and easily understood by my ESL students. Consequently, I began creating my own videos to supplement my ESL students’ learning needs in chemistry. Since then, I have gone on to create over 200 videos, and I am still uploading content on a weekly basis. A few months ago, I was surprised to watch one of my video tutorials surpass one million views on YouTube.

 

 

I count myself fortunate to be contributing to the growing online library of instructional videos that help make education accessible for all.

Research

My interest to understand what it takes to be a great teacher recently lead me to the University of Michigan where I earned an M.S. in Chemistry in 2018. As a graduate student, I was a member of in chemistry education. I completed a study that investigated the topic-specific pedagogical content knowledge (PCK) of graduate student teaching assistants in organic acid-base chemistry. A manuscript of this study is currently under review.

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The Shultz group is young, only a couple of years old, but they are already making a name for themselves in the chemistry education community with some

I am now back in the high school classroom, and my research with the Shultz Group has shaped the lens through which I see my work. In future posts, I look forward to sharing how a thorough understanding of PCK has the potential to help us to grow into better chemistry teachers.


References

Grossman, P. L. (1990). The making of a teacher: Teacher knowledge and teacher education. Teachers College Press, Teachers College, Columbia University.

Park, S., & Oliver, J. S. (2008). Revisiting the conceptualisation of pedagogical content knowledge (PCK): PCK as a conceptual tool to understand teachers as professionals. Research in science Education, 38(3), 261-284.

 

Career Profile: Postdoctoral Research Fellow - Dr. Nakita K. Noel

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Dr. Nakita Noel in the laboratory

I’m currently a Postdoctoral Research Fellow at the Princeton Research Institute for the Science and Technology of Materials (PRISM) working on metal-halide perovskites.

The term perovskites encompasses all materials that have the crystal structure ABO3, where the A and B sites are occupied by cations and the anion is most frequently O2-. Metal-halide perovskites are a category of perovskite materials with an ABX3 crystal structure, where the A site is occupied by a monovalent cation, the B site by a divalent cation and the X site by a halide anion. Perovskite such as these have important applications in optoelectronic devices. My specific focus is on using them in solar cells and light-emitting diodes (LEDs), and in doing this, I work very closely with physicists, chemists, material scientists and engineers on a daily basis as this area of research is very inter-disciplinary.

 

Did you get to your present position because of your background in chemistry and area of specialization or did life experience(s) take you there?

It’s probably a mixture of my background in chemistry and my area of specialisation to be honest. At the undergraduate level I did degrees in both chemistry and physics and spent time as a research assistant in chemistry doing projects which were at the intersection of physical and inorganic chemistry. I love chemistry and physics equally, so I really struggled to choose one or the other. This is what really makes my research area perfect for me. I get to manipulate and explore the chemistry of the perovskite material, while using it to study device physics. It’s really a very happy marriage of both subject areas I love.

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Dr. Noel spin-coating perovskite films in a glovebox.

 

In which area of chemistry did you specialize?

I specialised in physical and inorganic chemistry as an undergraduate and carried out research which was an intersection of both areas. Some of my favourite classes were on spectroscopy. It’s an amazing set of tools that give you a world of information, a bit like clues to solve a puzzle. It’s really intriguing. I’ve also done some lab teaching and demonstrations for inorganic and physical chemistry courses which I quite enjoy. It has definitely been very rewarding to see students have that “aha!” moment and be excited about their work. I did my PhD in Condensed Matter Physics at Oxford where I was one of the only students coming from a chemistry background. Largely because of the project which I chose, I still did quite a lot of chemistry. I started working on metal-halide perovskites for optoelectronic applications. A large part of the work that I did during my PhD involved the synthesis and characterisation of various inorganic and organic-inorganic hybrid perovskite materials. The characterisation of these materials involved doing a lot spectroscopy. I’ve also done a great deal of work on improving the interfaces in perovskite solar cells through chemical interventions such as charge-transfer doping and surface passivation, which effectively reduce non-radiative recombination of charges at the interfaces in solar cells, allowing more efficient conversion of light into electrical energy. Another area of research that I’m involved in is manipulating the crystallisation of thin films of the material through solvent interactions. For example, changing the nature of the solvent affects things like the colloid concentration in precursor solutions, and the kinetics of the crystallisation process, which has a marked effect on the optoelectonic quality of the resulting perovskite thin-film. Most of these things involve a fair bit of organic chemistry, so while I’ve specialized mainly in physical chemistry and inorganic synthesis, I’ve dabbled in organic chemistry quite a lot in recent years.

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Dr. Noel in a clean room looking at the film after having just deposited it.

 

Do you use chemistry on a daily basis? Describe what you do on a day-to-day basis.

The answer to this question varies, as it depends entirely on what project I’m working on at any given time. Currently, the answer is yes. Whether it’s developing new solvent systems for metal-halide perovskite materials or developing and testing new interface modifications for perovskite-based devices, you can usually find me in the wet-chemistry lab. After depositing the perovskite films, then comes the characterisation where I really get to test my theories. That typically involves doing a lot of photoluminescence and infra-red spectroscopy, as well as X-ray diffraction and electron microscopy. More recently I’ve found my way back to looking at solid-state NMR as it’s one of the more powerful tools I can use to answer my current research questions. Subsequently, I usually incorporate my test films into either solar cells or LEDs to investigate whether any new materials or processes I’ve introduced have a positive effect on the efficiency and stability of devices. I place strong emphasis on applications in my work. After all, most people in this field are trying to save the world through making solar power cheaper and more efficient! Of course, after each of these steps there is lots of data analysis to be done to determine whether moving on with the current idea is useful, or if it requires going back to the drawing board. Keeping up with scientific literature is also extremely important, so I try to read a couple relevant papers a day. It’s very hard to keep up in the field of perovskites as it’s a very fast-paced field where many papers get published every day, but it’s also important because sometimes you get your best ideas from realising there’s a gap in the research space and thinking about how best to fill it.

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Large area film which has been deposited using a non-toxic perovskite solvent.

 

Describe the personal skills that have played an essential role in your present position.

Being able to take a step back, shake off failed experiments and reimagine feasible solutions is definitely a skill that I’ve had to develop.

It’s very important as a researcher to be able to communicate both your ideas and your results clearly. Being an effective communicator is key. Another vital skill is the ability to work well as part of a team, in addition to being able to work well individually. The best research is often highly collaborative. Being able to coordinate various aspects of a project and getting a wholistic view of a problem typically leads to the best solution. Perseverance is also important. I would say about 75% of the time, things don’t work instantly. Being able to take a step back, shake off failed experiments and reimagine feasible solutions is definitely a skill that I’ve had to develop.

 

What advice do you have for those who wish to pursue this or some other non-traditional career path?

Whether traditional or not, make sure you love what you do. I’m very lucky to be excited about my research. Regardless of what path you take, it’s not always going to be easy. Loving what you do and having purpose in doing it is what gets you through the rough patches.

 

How and where can readers learn more about this type of career?

Positions like this are usually stepping stones for younger researchers who want to continue research in either academia or industry, and there are positions like this in practically every field of study.

For specifically the area of research that I’m involved in, Dr. Sam Stranks provides a good introduction in his Ted Talk (below) on the subject. 

 

Another good video (below) features scientists at the National Renewable Energy Lab highlighting the potential of perovskite solar cells. 

is a great blog that offers good tips and resources for researchers. 

An additional video (below) that I recommend is interesting because of all the predictions made in it have come to pass. It is from my previous research group at Oxford. It was a perspective video for one of Henry Snaith's articles in the Journal of Physical Chemistry Letters. He is really a juggernaut in the field. I think this video covers everything that may have been missed in the others, and gives a really nice perspective with regards to how quickly the field has grown.

 

Are there any other thoughts or lessons learned that you would like to share with our readers?

If you do decide to get into research, make sure you do it in an area that you love. You don’t always have to fit into a specific mould and be, for example, strictly a chemist, or strictly a physicist. There’s always an area of research where you can find a happy middle ground. No matter what you do, you will always encounter naysayers who will try to discourage you or say that you can’t do something. You alone have the ability to prove them wrong.


Editor's Note:  is a project intended to help teachers and their students understand the wide variety of career paths available in the field of chemistry. If you know a professional in a chemistry related field that would be interested in authoring their own career profile or if you have a specific career you would like us to highlight, please reach out to us using our 


NSF Engineering Research Center RET Opportunity

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CISTAR LOGO

The Center for Innovative and Strategic Transformation of Alkane Resources (CISTAR), an NSF Engineering Research Center at Purdue University, is hosting an exciting Research Experience for Teachers (RET) during the summer of 2019.

The program is for six weeks: May 28 - July 3, 2019.

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More information about CISTAR is . Our team will make every effort to match those selected for the CISTAR program with a faculty member working on a research program of mutual interest.

include a letter of support from a Principal or Senior Administrator, a resume and current photo. Applications are due February 15.

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Event Type: 
professional development program
Time: 
Tuesday, May 28, 2019 - 07:00 to Wednesday, July 3, 2019 - 07:00

Capping Off a Unique Redesign of the Laboratory Curriculum

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titration set up image

A few years ago, the faculty in our department at  decided to switch to an atoms first approach to the General Chemistry course. We took advantage of this change to systematically redesign the first semester of the laboratory curriculum to be a true “laboratory course” that focuses on laboratory practices, techniques, and equipment rather than on chemical theory.

The general theme for the sequence is quantitative analysis which allows us to thoroughly discuss many generalizable topics surrounding laboratory science such as measurement uncertainty, propagation of uncertainty, and statistical handling of uncertainty. These ideas apply to any field that uses empirical data which helps make our laboratory curriculum more relevant to the wide range of majors taking the General Chemistry courses.

Prior to the experiments discussed here, the students complete laboratory exercises in calibrating and using laboratory equipment such as the electronic balance, volumetric pipets and burets, the proper use of a volumetric flask to prepare solutions, and basic titration procedures including standardizing a sodium hydroxide solution and its subsequent use to analyze household vinegar (see Figure 1). For each piece of equipment used the students are instructed not only in the fundamentals of using the equipment, but also the basic features, the measurement tolerances, and the rationale behind any specific laboratory protocols for using the equipment such as weighing by difference, pretreatment of volumetric pipets and burets, and the stepwise with swirling procedure for filling volumetric flasks.

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Figure 1: Core Quantitative Analysis Exercises

 

After completing these exercises, the students are tasked with analyzing a sulfuric acid solution where the concentration of the sulfuric acid solution is too high to be conveniently analyzed with the standardized sodium hydroxide solution available to them. To complete the task, students must first quantitatively dilute the stock sulfuric acid solution which illustrates a practical use for the quantitative transfer and solution preparation techniques from previous exercises. The students then quantitatively transfer aliquots of the diluted acid solution to Erlenmeyer flasks and titrate the diluted acid solutions with the sodium hydroxide solutions to a phenolphthalein (PHTH) endpoint. A flowchart illustrating the procedure is shown in Figure 2.

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Figure 2: Procedure for Analysis of H2SO4 with NaOH solution

 

After the diluted acid solution concentration has been determined, the students can then calculate the stock acid concentration using the dilution ratio from the first stage in the procedure. This experiment serves as an effective capstone exercise for the first-semester laboratory to reinforce the quantitative procedures from previous exercises while also introducing non-1:1 stoichiometry in an acid-base titration, the role of dilutions in chemical analysis, and the idea of back-calculation to determine the stock concentration.

At the beginning of the second-semester, the quantitative analysis procedures are revisited in a second capstone exercise. The students first quantitatively prepare a stock solution of KHP using the electronic balance and a volumetric flask (Figure 3).

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Figure 3: Preparation of a Stock Potassium Hydrogen Phthalate solution

 

The students then titrate the stock KHP solution using a standardized sodium hydroxide solution to a PHTH endpoint that requires them to refresh their skills using the volumetric pipet and buret as well as requiring them to recall their knowledge regarding titration procedures and acid-base stoichiometry (Figure 4).

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Figure 4: Procedure for Titration of Student-Prepared KHP Solutions

 

The students gauge their success for this exercise by determining the %Relative Average Deviation value (%RAD) for the titration activity to quantify the level of precision of their titration process and the % Difference value (%Diff) between the nominal stock concentration calculated from the preparation stage and the experimental concentration from the titration stage as a means to measure their success for the entire procedure. We use tolerances of ≤1%RAD to indicate a “good” level for student precision in the titrations and ≤1%Diff agreement between the two concentration values to show a successful overall procedure.

Taken together, the early exercises with individual pieces of equipment, the two basic titration activities, and the two capstone titration exercises have been effective in helping students gain the necessary familiarity with quantitative laboratory procedures that they can maximally benefit from later experiments (see Figure 5). The constant revisiting of the core techniques allows students ample time to learn the fundamentals of each technique as well as begin to view them modularly since different core skills may be employed for nominally similar experiments.

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Application of core skills in analysis activities

Figure 5: Application of Core Skills in Analysis Activities

 

It has been our department’s experience that students don’t have the needed “muscle memory” to be able to think much during the titration procedures until the sulfuric acid experiment. Until that point, they are largely following the written procedures by rote. This past Fall semester, I had some fun “freeing their minds” by asking my students to put away their lab manual for the sulfuric acid experiment and complete the activity using their experience from previous activities and any knowledge gained while completing an online pre-experiment assignment. This is announced during the pre-experiment discussion so that students will know to pay close attention. During the discussion, the full procedure is presented in detail and the presentation ends with an overview of what was to be accomplished that day (Figure 6). Our labs are outfitted with computer monitors and this slide is left on the screens as a quick reference until all students have begun titrating their dilute acid samples. After only a short period of discomfort in being untethered from the stepwise instructions in the manual, all students in three sections of laboratory were able to complete the activity successfully.

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Figure 6: Reference Slide for “Manual Free” Sulfuric Acid Activity

 

Between the Fall and Spring semesters, our institution has a 5 week break to allow for Winter term online courses and the students forget much. We use the second capstone activity using KHP to refresh the student’s quantitative analysis skills. Students are allowed to use the procedure in the lab manual for this activity since most of them require that crutch. The KHP activity also serves as a quick “crash course” in the fundamentals of quantitative analysis for students who have taken the first semester laboratory some time ago or at another institution. The remainder of the second-semester laboratory course follows a more traditional approach in that it includes experiments designed to support current topics in the lecture course. We do include two consumer-oriented analyses for purposes of timing certain experiments to correlate with the lecture schedule and quantitative analysis procedures are also featured in late-semester equilibrium studies. (Figure 7).

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Figure 7: Second-Semester Activities Using Quantitative Analysis Skills

 

Having already developed substantial skill in quantitative procedures and some level of confidence, the students are able to better focus on the chemical theory in these later experiments since the core procedures have become somewhat trivial to them at that point. Admittedly, some students become bored with titration by the end of two semesters. Some of this disinterest can be alleviated by stressing the versatility of the technique and including examples of how titration is used in various fields. Some students do notice how “nice” it is to not have to constantly learn new procedures. The lack of a need to discuss laboratory techniques in the later experiments frees up valuable pre-experiment discussion time to better explore side-topics or to more firmly cement the connection between the laboratory activity and the current lecture material. The inclusion of the consumer-oriented analyses also helps to maintain student interest throughout the sequence.

Our faculty are generally pleased with the results. At the start of the second semester, students are much more capable and confident in the laboratory. By the end of the second semester, most students become quite efficient and can complete a basic, three-sample titration procedure in approximately one hour from set-up to clean up. Students seem better able to actively process while working on the capstone and later activities often asking perceptive questions about the experiment rather than the typical, low-level “what do I do next?” type questions of disengaged students. While not expressly designed for chemistry majors, the students in our department who go on to take the upper-level Analytical and Physical Chemistry courses more easily adapt to the stringent quantitative procedures required in those courses since it only requires that they fine-tune skills developed during the first-year laboratory courses.

Overall, the two capstone exercises involving titrations are effective activities to round out a sequence focusing on quantitative procedures. They also serve as a springboard to enhance more chemical theory rich activities by diminishing the need to reteach laboratory techniques. Even in a traditional laboratory approach where the quantitative techniques are presented as part of a titration experiment rather than treated separately beforehand, either of the capstone exercises could be used as a follow-up activity to review skills or as a laboratory practical exercise for student and/or curriculum assessment.


Acknowledgements 

The author would like to thank Ms. Allison Tarvin for her blog post, , the inspiration to share the story of our laboratory curriculum redesign and ChemEd X Editor, Deanna Cullen, for many helpful communications during the drafting of this document.

Safety: 

Periodic Trends Guided-Inquiry Activity

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periodic trends student materials

Trends related to placement of elements on the periodic table are often taught using diagrams in a textbook. Students often memorize trends, but to get a true grasp of their meaning and what causes certain patterns is best understood when students create their own models and discuss the patterns with others.

This inquiry activity was designed to be carried out in ninety minutes, with few supplies, yet produces an accurate visualization of the trends. The tiered levels of questions and reflection may be used to differentiate between introductory, advanced first-year, and AP chemistry. Students create their own diagrams using blank periodic tables of the main group elements in the first four periods. Four models are developed: atomic radius, ionic radius, ionization energy, and electronegativity. 

The activity detailed here is different from other readily available inquiry-based activities as it seeks to support student learning and concept development by using an actual Periodic Table as a template. By mapping specific trends directly onto a blank Periodic Table, the activity

  1. Uses the Periodic Table as a foundational aspect of the major trends, allowing for students to make connections between placement on the Periodic Table and a specific trend
  2. Supports development of a causal understanding of why trends change as they do through the creation of a graphical representation
  3. Reduces the cognitive load for all students by linking trends directly to the periodic table, a tool available to students throughout the chemistry course. The Teacher Guide accompanying this activity further supports teachers in determining the most appropriate level at which to address student learning needs through a list of suggested questions and discussion starters.
  4. Allows for students to develop a product (Periodic Table colored-coded per trend) so that students readily understand where, why, and how in terms of the development of the picture/Periodic Table created.

Additionally, the Teacher Guide accompanying this activity supplies questions and dialogue intended to support those new to teaching periodic trends and/or new to using guided inquiry-based activities.

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Figure 1: Blank periodic table for students to use in the Introductory Investigation. There is a separate table for each of the four trends, with the headings changed as appropriate.

 

This activity is designed for high school or college general chemistry classes. It is presented following introductory lessons about the history of the periodic table and the significance of periods and groups in terms of valence electrons and energy levels, but before any trends have been discussed. The students begin the activity individually during class by developing predictions, then creating four models, one for each periodic trend. The students then work collaboratively in groups of three or four to analyze trends in each model and develop conclusions. The groups extend and reinforce their conclusions through a series of thought-provoking questions. Finally, the groups share their results with the class and the class reflects on their learning.

The supporting information includes black-line masters of all of the materials used by the students, and a teacher’s guide that include suggested guided questions and answers, differentiated by level. 

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Figure 2: Sample of data table provided to students

 

The Activity

This section is completed individually. The activity begins with four blank periodic tables (Figure 1) that include boxes for the main-group elements in the first four periods, plus data tables (Figure 2) with the values for each trend. The values in the data tables are the most common found in high school textbooks.1, 2 For the first model, atomic radius, the students use a metric ruler to draw a dot measuring up from the bottom of the box a distance marking the diameter of each element. Next they hand-draw a circle using the dot and bottom of the box as a guide for the height of the circle. (Figure 3) It is important to point out that the measurements are not the actual size of atoms, so a scale is included.

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Figure 3: Sample of completed atomic radius table. Color is optional.

 

For the second model, students will use the metric ruler to draw vertical “energy bar” lines proportional to ionization energies (Figure 4).

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Figure 4: Sample of ionization energy bars. Advanced or AP discussion includes the irregularities in group 13 and group 16. Discussion starters and explanations are included in the Teacher’s Guide.

 

For the third model, the students will again use the metric ruler to create circles with a diameter proportional to the diameter of each ion, similar to what was done in Part 1 (Figure 5).

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Figure 5: Sample of Ionic Radius. Lively discussion ensues as students try to explain the unusual trends across periods.

 

 

In the fourth model, students will again use vertical lines proportional to electronegativity values (Figure 6).

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Figure 6: Sample of Electronegativity table. Note that the electronegativities of the noble gases are zero, effectively.

 

Group Discussion and Class Reflection

After the independent construction of the four models, students are divided into groups of three or four. Each group is prompted to describe the trends that they observe for each of the four models.

Each group discusses the follow-up questions, while each student records individual answers on their follow-up sheet. Questions are differentiated depending on the level of students. For example, first-year students will understand that atomic radius increases from top to bottom down a group and decreases from left to right across a group, where advanced or AP students can combine two trends to conclude that atomic radius increases diagonally from top right to bottom left. This makes the activity applicable for varying levels.

The activity is concluded as students present their observed trends to the entire class. The teacher can facilitate discussion using the appropriate-level reflection questions. Several methods for facilitating reflection, as well as sample questions and suggested answers are included in the Teacher’s Guide for this activity.

First-year students have shared some excellent observations. One group noticed that the size of ions going across is unusual, but it does follow a pattern. The size of ions going across a row went from smallest to largest based on ionic charges. For example, element number 7 has an ionic charge of -4, and is the largest in period 2. Element number 6 has an ionic charge of +4, and it is the smallest. Considering the ionic charges, the pattern in size is, from largest to smallest across the period of main group elements, -4, -3, -2, -1,+1, +2, +3, +4. The class then went on to notice that the size had to do with how many electrons are lost or gained.

If this topic is taught after electron configuration, advanced/AP students can easily visualize the anomalies in ionization energy in Groups 3 and 5, and understand that the electron configuration explains this phenomenon.

This activity has been piloted by multiple teachers in classes of varying levels. The teachers have reported that the activity is inexpensive, easy and time-efficient for the students to complete, and led to good discussion and comprehension based on answers to guided questions and follow-up assessments.

Log in to obtain access to two levels of the student document and a teacher document in the Supporting Information.

Cited Articles

1- Brown, T. L.; Lemay, H.E. Chemistry: The Central Science 12 ed.; Prentice Hall: New York, 2012, p 261.

2 - Buthelezi, T; Dingrando, L; Hainen, N; Wistrom, C; Zike, D. Chemistry: Matter and Change 8th edition Glencoe/McGraw Hill: Columbus, OH, 2007, p 194.

Concepts: 
atomic radius
electronegativity
ionic radius
ionization energy
periodic table
periodic trends
Procedure time: 
90 minutes
Prep time: 
10 minutes
Time required: 

The activity is designed for two, 50-minutes class periods or one 90 minute period. The individual sections can be completed in one 50-minute class period. The concept formation, group sharing and reflection can be completed in another 50-minute class period.

Materials: 

For each student: 

1 Ruler

4 Blank periodic tables (one for each of the following: atomic radius, ionic radius, ionization energy, and electronegativity) of the main group elements in the first four periods.  (in Supporting Information)

Procedure: 

The activity begins with four blank periodic tables that include boxes for the main-group elements in the first four periods, plus data tables with the values for each trend. This section is completed individually. The values in the data tables are the most common found in high school textbooks. 

In Part 1, atomic radius, the students use a metric ruler to draw a dot measuring up from the bottom of the box a distance marking the diameter of each element. Next they hand-draw a circle using the dot and bottom of the box as a guide for the height of the circle. It is important to point out that the measurements are not the actual size of atoms, so a scale is included.

In Part 2, students will use the metric ruler to draw vertical “energy bar” lines proportional to ionization energies.

In Part 3, the students will again use the metric ruler to create circles with a diameter proportional to the diameter of each ion, similar to what was done in Part 1.

In the fourth model, students will again use vertical lines proportional to electronegativity values.

See the student and teacher documents for the questions and discussion portion of the activity.

 

Questions: 

See the Student and Teacher documents.

Preparation: 

Make copies of student worksheet, data tables and blank main-group tables. 

Attribution: 

Dr. Patrick Harvey, Dr. Amanda Edwards, Dr. Lori Maffe helped pilot the activity. Tobie Hendricks, Dr. Michelle Head and Dr. Gregory Rushton supported me in writing the activity.

The Blue Butterfly Effect

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Blue Morpho Butterfly Wings

The June, 2018 issue of the Journal of Chemical Education contains an article that describes a simple, yet fascinating experiment that you and your students are going to love! It involves the use of butterfly wings from the genus Morpho.1 The wings of these butterflies display the most beautiful blue color I’ve ever seen. I purchased some of these wings2 so I could observe them and also to see what happens when some methanol is dripped onto these wings:

What gives these wings their vivid blue color, and why do the wings change color when methanol is dripped onto them?

First, let’s discuss why the wings are blue. Remarkably, the stunning blue color is not due to chemical pigments, but rather from millions of nanoscopic structures called lamellae that are embedded on the wings (Figure 1). The lamellae contain several alternating regions of ridges and air gaps. The ridges and air gaps are nanoscopic in size: small enough to diffract visible light. Any color of light – except for blue – that interacts with the lamellae is cancelled out due to destructive interference. However, when blue light strikes the lamellae it is amplified via constructive interference. These effects cause the wings to appear an intensely blue color. Color that arises in due to structural elements rather than pigmentation is called structural coloration.3

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Schematic of lamellae

Figure 1: Schematic of lamellae. (Left) a single, nanoscopic structure. (Right) Several lamellae.

The authors of the J. Chem. Educ. article note that the central wavelength of light, λImage may be NSFW.
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, scattered by the lamellae can be calculated using the following equation:1

λ = 2(n1d1+ n2d2)             Equation 1

Where d1 and d2 are the dimensions of the air gaps and ridges, while n1 and n2 are the refractive indexes of the air gaps and ridges, respectively. Plugging in the known values for the dimensions (54 nm for ridges and 142 nm for the air gaps)1 and refractive indexes (1.56 for the ridges and 1.00 for air)1 we calculate that the scattered light is expected to be centered at 452 nm, which is blue light:

λ =2[(1.00)(142 nm) + (1.56)(54 nm)] = 452 nm

We can also use Equation 1 to describe the color change that occurs when the wings are wetted with other substances such as methanol. When this is done the gaps between the ridges become filled with methanol instead of air, which changes the refractive index of the gaps. Using the value for the refractive index of methanol (1.326)1 rather than air in Equation 1, we obtain the result that the center of the wavelength of scattered light should be 545 nm, consistent with a greenish color:

λ = 2[(1.326)(142 nm) + (1.56)(54 nm)] = 545 nm

After I observed the color changes that occur on these wings upon adding methanol and other alcohols, I began to wonder what would happen if the wings were soaked in liquid nitrogen. Here’s what I observed when I did so:

Taking into consideration the refractive index of liquid nitrogen (1.200)2 and using Equation 1, a central wavelength of 509 nm is obtained:

λ=2[(1.200)(142 nm) + (1.56)(54 nm)] = 509 nm

This value harmonizes well with the brilliant green color observed when these wings are dipped in liquid nitrogen. The fact that the wings appear somewhat yellow-green in color when soaked in methanol but more blue-green when soaked in liquid nitrogen is consistent with the calculations above.   

Finally, these wings are very difficult to wet with water:

This effect results from a combination of the high surface tension of water and the very large surface area the millions of lamellae impart to these wings. I like to think of surface tension as the energy required to get a liquid to “spread out” over a certain area. Therefore, because water has a high surface tension (72 mJ m-2),4 to it resists “spreading out” on surfaces – it tends to “bead up” instead. The lamellae on the Morpho butterfly wings mean there are hundreds of millions of crevices on the wing surface, which gives these wings enormous surface area. Because water has such a high surface tension and therefore does not spread out easily, it cannot penetrate all the nooks and crannies introduced by the lamellae. Thus, it cannot wet the wing. This probably comes in handy for the Morpho butterflies, because they live in rainy tropical regions.3 On the other hand, methanol (22.5 mJ m-2)4 and liquid nitrogen (8.9 mJ m-2)5 have considerably lower surface tensions, and they therefore easily wet these wings.

I have found that people young and old enjoy viewing experiments with the blue butterfly wings. In the video below you can view some of these experiments explained and explored in a bit more detail. Let me know if you try experimenting with blue Morpho butterfly wings – especially if you learn something new. Happy experimenting! 

Acknowledgement: I wish to thank Bruce W. Baldwin for helpful discussion.

 

References

1. B. Bober, J. Ogata, V. Martinez, J. Hallinan, T. Leach, and B. Negru, , Journal of Chemical Education, 2018 95 (6), 1004-1011.

2. I was able to purchase 50 wings for about $50 at The Butterfly Company. When handled carefully, the wings can be used several times. See: (Accessed 1/29/19)

3. P. Vukusic and D.G Stavenga, , Journal of the Royal Society, January 2009.

4. G. Vazquez, E. Alvarez, and J. Navaza, , Journal of Chemical & Engineering Data, 1995 40 (3), 611-614.

5. Dortmund Data Bank, (Accessed 1/29/19)

Boltzmann Bucks—Helping Students Conceptualize Entropy

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Boltzmann Bucks provided to students

Each year, my honors chemistry class eventually gets to the point where thermodynamic quantities and the relationships between them are introduced. For many students, the very nature of the ideas within thermochemistry often creates a sense of overwhelming abstraction that is difficult to overcome. Of all these ideas, the concept of entropy has given both my students and me the greatest trouble. This year, I was determined to change that.

I wanted to better understand the concept of entropy myself and search for more effective methods teaching it to novice chemistry learners. Fortunately, thanks to Theresa Marx and Erica Posthuma-Adams, I was introduced to an engaging activity that really improved how my students (and me) think about entropy—the Boltzmann Bucks game. If you are looking to go beyond using traditional, arguably misleading, definitions of entropy involving “disorder” and “messy bedroom” analogies, this activity can serve as a wonderful opportunity for students to more accurately conceptualize entropy.

As our thermochemistry unit approached, I started to take a closer look at how and why the concept of entropy was derived in the first place. Until that point, certain aspects of how I taught entropy could be summarized by the following definitions and ideas:

Entropy is…

  • A measure of disorder
  • A measure of the dispersal of matter and energy
  • A measure of chaos

Changes in entropy

  • Increase in moles from reactants to products (increase in entropy)
  • Release of heat—exothermic (increase in entropy)
  • Lower-energy to higher-energy state of matter s → l → g (increase in entropy)

Direction and Entropy (Spontaneity)

  • Reactions that result in an overall increase in entropy tend to be favorable
  • The increase in entropy accounts for the irreversibility of natural processes

Whenever a student would ask a thoughtful question such as, “what do you mean by disorder?”, I would resort to common examples and analogies such as,

  • Your bedroom always goes from clean to messy (low to high entropy)
  • Entropy is like an incomplete jigsaw puzzle (incomplete puzzle has higher entropy than completed puzzle)
  • Waterfalls always flow downhill
  • At 20 0oC, ice melts
  • When a tire is punctured, air always leaves from the tire to the surroundings

Regardless of the analogy or example, they were simple to use due to their familiarity with students’ past experiences and I could get students to consistently predict when entropy was increasing or decreasing throughout a process. However, I never truly felt as though my students understood the overall concept of entropy and its explanatory role for why natural processes tend to go in one direction and not the other. As a teacher, it felt more like I was just giving them a word to know, telling them when it is increasing or decreasing, and then just informing them that the universe tends to favor certain directions for processes. It was unlike any other feeling I have had teaching a specific concept in chemistry; completely disconnected from understanding but somehow tricking myself and my students into thinking understanding was taking place.

To relieve my own personal stress with this feeling of inadequate understanding, I started to look more closely at the concept of entropy through various resources. It wasn’t long before I realized an essential characteristic of entropy that had been completely vacant from my own understanding and, subsequently, my teaching—its simple relationship to probability.

Suddenly, terms that I had heard before but never took the time to fully comprehend, such as microstates and distributions, started to bring a sense of clarity to a topic that had always been fuzzy to me. But developing an understanding of these terms, their relation to probability, and how it all fit together to describe the concept of entropy was not an easy task for me. So how was I supposed to get my students to arrive at a similar revelation?

Instead of scouring the Internet for some kind of activity, I reached out to my PLN of educators and, as usual, they did not disappoint. It turned out that there was a JChemEd article, Give Them the Money: The Boltzmann Game, a Classroom or Laboratory Activity Modeling Entropy Changes and the Distribution of Energy in Chemical Systems,1 describing an activity that appeared to be exactly what I was looking for. While I strongly encourage you to give the article a read for more details, I will try to summarize the activity and some of the key points made in the article.

What is the game supposed to model?

What the Boltzmann Game models is how energy is distributed in real chemical systems. In particular, the authors suggest that this game simulates the harmonic oscillator model of vibrational excitation, which describes how energy is quantized and constantly being exchanged between the molecules of a system.

How does this game compare to other activities meant to model this concept?

"what seems to be lacking are simple quantitative activities that students can participate in that effectively convey the essential probabilistic nature of entropy"~Hanson and Michalek on why they developed the activity

The inherent value of the Boltzmann Game stems from the lack of simple, inexpensive, and engaging classroom activities that appropriately model the concept of entropy. More specifically, the authors suggest, “what seems to be lacking are simple quantitative activities that students can participate in that effectively convey the essential probabilistic nature of entropy".

OK, so what does it look like?

After a brief conversation (optional) with students about the random nature of how energy is exchanged and distributed at the particle level, students are told they will be modeling this concept by playing a game that is grounded in probability and randomness—rock, paper, scissors. Here is a synopsis of how the game is set up, played (see figure 1), and recorded:

Game Setup

  • All students will form teams of two. It doesn’t matter whom you are paired up with since you won’t be together for long.
  • Every student receives one Boltzmann Buck (B$) (found in supporting information), which represent 1 packet (quantum) of energy.
  • Students will form 2 circles; 1 circle within the other and each pair of students will need to decide who will be in the “inner ring” and who will be in the “outer ring.”
  • The “inner ring” students from all teams form a circle facing outward while the “outer ring” students will form a circle facing their partner.
  • The result should be two circles, with the two students in each team looking at one another.

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Figure 1: Rules of Rock-Paper-Scissors

 

After all rounds were completed, students came back to the classroom and were told to copy the data into their notebooks. The following table reflects the data we gathered that day (figure 2).

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Figure 2: Data from my class

Without any class discussion, I asked my students to answer the following questions:

 

What does energy have to do with probability?

Even though we had previously discussed the idea that energy is exchanged randomly, I could see that statement not fully being grasped prior to the game. However, after playing the game, many students were trying to make sense of the relationship between energy and probability in meaningful ways. Though I wish I had recorded these answers, the following response from one student taken directly from the JChemEd article was similar to what I heard from my own students: “Probability comes into play with energy because there is a chance that you will gain or lose your energy, and there is a chance of both for every molecule that’s floating around other ones just like in the game. You could gain, lose, or simply stay the same.”

Why isn’t the most probable distribution of money one where all players have the same quantity of money?

What I loved about this question was how many students intuitively came up with a similar explanation. The majority of them realized that the number of ways for the money to be distributed equally between all players was incredibly small compared to other potential outcomes. It simply was too improbable. Understanding the role of probability with respect to the distribution of money was essential if they were going to connect how this game modeled the probabilistic feature of entropy.

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Figure 3: One Boltzmann Buck is given to each student at the beginning of the activity.2 (Reused with permission) 

After a brief class discussion about their answers, I followed up with another question to see if they could apply new information to their model.

Would the energy distribution be any different if more energy was added (I give you more B$)?

While this question was not as widely understood initially by my students, several of them realized that if I inserted more money (energy) into the game, there would be a greater distribution (a higher average) and the number of players with zero would decrease.

It was at this point that I introduced the thermodynamic terms microstate and distribution. In short, I talked about how the number of distinct ways energy can be distributed throughout a system is known as a microstate. In our game, this would be like describing how much B$ each person had at any given point in time. Since calculating the possible number of ways each person could have B$ can quickly get out of hand, our game focused on collecting information on the distributions of B$ (energy). As the data suggested, some distributions of B$ (energy) were more probable than others. This increase in probability of energy distribution directly corresponds to an increase in entropy. Based on this information, I finally asked them to describe how entropy is intimately related to probability in their own words.

Though we did not get in to the details of how we could quantify the number of microstates using Boltzmann’s entropy formula (S = k·lnW), I thought it would be useful for students to calculate the number of ways (microstates) a particular distribution of money could be made. By doing this, they could visibly see an actual quantity for a particular distribution and compare it to other distributions. Through comparisons, they could literally see that some distributions were simply far more probable than others. To determine these quantities, I showed them how they would need to involve the use of factorials.

For example, the number of ways to achieve the distribution from my “most probable distribution” column in Figure 3 would be calculated as follows:

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This distribution can occur in roughly ninety billion ways; far more than any other distribution.

Calculating the number of ways a particular distribution could occur was also useful because it forced students to realize that different distributions were not a matter of possibility, but probability. When discussing topics such as entropy and spontaneity, we often describe one direction of a certain process as impossible. For example, we point to extreme examples like dropping a glass cup and watching it shatter in to a million pieces. We declare that the reverse process, the million pieces coming back together to form the original glass cup, is impossible! Or how energy always flows from warmer objects to colder objects and the reverse is impossible. However, once we understand the probabilistic nature of entropy, we make the shift from declaring particular directions as impossible and instead, view them through the lens of being so incredibly improbable that we can be reasonably confident it will never happen. Viewing the directionality of processes this way may seem trivial since the end result is essentially the same, but simply declaring one direction as impossible without adequate explanation as to why we believe this completely removes any need for understanding why certain processes tend to go in one direction and not the other.

So How Did This Game Impact Understanding of Entropy?

Getting my students engaged with this activity and the subsequent conversations that followed, opened up doors for the types of questions I could ask my students with respect to explaining why spontaneous reactions tend to increase in entropy. In the past, I would ask a simple question like, “which state of matter has a higher entropy—solid or liquid?” Nearly all students would answer correctly but when pushed to explain their answer, they would simply rely on concrete explanations such as, “the particles in a liquid are more dispersed.” In our recent exam, I asked the exact same question and got answers that absolutely blew me away (see figure 4) compared to previous years. Students were including ideas such as probability and comparing the possible number of microstates and distributions of matter in a liquid compared to a solid. This was something I had not seen before and it was obvious their overall explanatory abilities regarding entropy had improved.

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Figure 4: Student quotes after completing the activity

Additionally, this new understanding helped them more easily conceptualize spontaneity and make predictions without simply resorting to algorithmic “tricks” I had relied upon in the past. More students were viewing problems related to entropy and spontaneity in a fundamentally different way than before.

The Boltzmann Game not only helped my students construct a more meaningful and accurate definition of entropy, it provided a memorable experience for students connect with their explanations regarding entropy in a more effective way. As stated by the authors, entropy is seen as a measure of “the number of ways a state can have the same overall distribution of energy”, and any differences of entropy are measures of the “relative probability of two possible distributions”. Statements like this would have gone right over the heads of my students had we not played this game. This realization was a game changer for me and I will most certainly do it again. Additionally, I plan to incorporate different uses of the game that were suggested by the authors such as modeling the exchange of energy between a system and its surroundings.

Log in to have access to Supporting Information: a pdf of Boltzmann Buck images from the original JCE article and a handout I use with students as we work through the activity.

1. Hanson, R. Michalek, B. Journal of Chemical Education. Vol. 83 (4), April 2006, p. 581.

2. The Boltzmann Buck is reused with permission from the Supporting Information of the activity outlined in the Hanson,  Michalek cited above. Copyright 2006 American Chemical Society.

Supporting Information: 
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Boltzmann Bucks Game - Student
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Boltzmann Bucks - Distribute 1 per student
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