Organic chemistry was when I fell in love with chemistry. Also known as Chem 210 at the University of Michigan, it was the first time I actually started to connect what was going on at the nanoscopic level to the macroscopic world. Since then, I’ve been hooked.
As a teacher, I have grown a lot over seven years (including student teaching). How do I get my students to make connections to the nanoscopic without, you know, curved arrow mechanisms? I have been fortunate throughout the years to piece by piece gain new perspectives that I thought I’d summarize and share with you - in fact, I’ve effectively rearranged my whole first year chemistry course to be built upon a progressively more in depth view of the nanoscopic. In this post, I will focus on only my reactions unit. This is in the second semester after students learn about the mole and empirical formula.
In our reactions unit in the second semester, we go all in.
First, students learn how to balance, classify reaction types, and predict products.
This part is where my former mentor, Julie Andrew of CU Boulder, really helped take this unit to the next level. She shared a lab with me (that I’ve edited from her original document) where not only do students practice predicting products, but they get practice in experiencing when predictions fail. Some of the reactions are designed so that they get results that DON’T match their predictions. This allows for students to (1) make a real conclusion if their predictions matched their observations and (2) ask new questions that lead me to showing splint tests. Here is an example. When students predict the products for the reaction of hydrochloric acid and sodium bicarbonate, they predict sodium chloride and carbonic acid, since they see it as a double replacement. This is 100% valid based on what they have learned. However, this is what actually happens: HCl + NaHCO3→ NaCl + H2O + CO2.
In our whole class debrief, we go through EVERY reaction after they share their data on the board. I tell them they are smart for making that prediction once they find it fails- it’s what scientists do ALL the time- make predictions based on prior knowledge to sometimes find that they were wrong. It is helpful to give them the "maybe" option. See a sample class data set below- this gave us great ways to start class conversations.
B. Here’s where we dive into the nanoscopic - the animation project. I introduce the project, and then do a few lessons first.
Lesson: Dissolving - ionic vs covalent compounds (edited from a posted PHET - credit is within the document). My students really struggled with the vocabulary of dissolve vs. dissociate, even though they could find errors in particulate diagrams. So the next day, this was their warm up. It was quite telling (PS- yes the phosphate has dissolved in water and has dissociated from the sodium. However, the phosphate ion itself doesn’t dissociate further).
Notes: Redox vs. Precipitation Reactions
Now, groups of 2-4 students choose two reactions from their previous lab to make animations to connect the nano and macroscopic representations. They must choose a precipitation reaction and a redox reaction. Here is a link to the videos they made.
One Bigger Con:
Time. It takes time to teach this and time to make the animation. I have posted a pseudo-POGIL-style PHET activity below that prepared students for animations. I also posted the project guidelines (thank you Julie Andrew at CU Boulder for the nuts and bolts of this!!!!!). Word of the wise: google slides is also awesome, and in some cases, more awesome than ChemSense referenced in the instructions.
A Few Pros:
Time “lost” in this project reaps benefits in dividends in stoichiometry. This is the first year (!!!) I’ve taught stoichiometry with BCA tables and the animation projects before were an unintentionally amazing scaffold. I have NEVER seen my students so successful with stoichiometry as I’m seeing now, and my hunch is that the animation projects helped make the BCA tables more accessible.
I sent the animations to MEL Science. They haven’t gotten back to us yet, but my students were pretty stoked to send off the animations to a company for feedback.
My Tweet | |
Their Response (so far) |
I hope this is helpful and sparks ideas for the future, and I’d love to hear more of what you do too!
