Day 23: Tic Tac Bounce with 9th Graders

Our last class together involved a lot of quantitative work—the first of that kind that the 9th graders had seen. We needed to do a bit more of that to finish out the unit, but I also didn’t want to overwhelm them with two days in a row filled with numerical problem solving. So we started today by gathering around one of the lab tables and looking at a tic tac as it bounced. Once they started noticing what I was seeing, I gave them a bunch to use on their own, and there were tic tacs flying everywhere. They climbed up to higher places to drop them farther, bounced them from one end of the table to the other, and basically just tried everything they could try.

Then we paused for a moment, and I told them to grab a whiteboard for each table and work on an LOL to represent it. I went to the front and drew an LOL shell with labels showing the first L should be the top of a low bounce and the second L should be the top of a later high bounce. Everyone bounded off to create the boards.

Of course, a few minutes later everyone was confused because the energy didn’t seem to add up. How could the second L have more Ug than the first if neither had any K? Before I could even make a suggestion on what to do next, they were already pulling out their phones and filming in slo-mo. At least one student even used Video Physics on the iPad to model the position of the tic tac versus time.

In the total chaos that was happening, the admissions tour stopped by, and everyone paused long enough for one student to explain (really eloquently!) what was happening. Then they went right back to filming, observing, and noticing. They quickly figured out that the spin had something to do with it, and a group with an especially good video used Air Play to get it on the front board. They decided the spinning was a kind of kinetic energy. I gave them the name “rotational kinetic energy”, and they updated their boards.


One group shared their final board to make sure everyone was on the same page, and then we went back to problem solving.

I hadn’t taught 9th graders physics before this year, so I wasn’t sure what to expect. They totally exceeded my expectations. The 9th graders might have more unevenness in the math comfort and experience that they bring to the class than older students that I’ve taught, but they are actually quite good at the physics itself. They notice things quickly, they are ready to extend their models (and don’t just rely on my having told them everything they would ever need to know), and they are resourceful and creative in their approach. It’s such a fun class to teach. I’m going to be so sad when our class ends at the end of December.

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