One of the interesting things about teaching long term is seeing how your activities, labs, tests, et. all grow over time. You learn new strategies, prescribed content changes, you mature and you change how you want to teach. I judge my past self harshly when I read old questions: "This was so ambiguous!" or "No wonder the students missed that part of the instruction, there is too much text." I try to save myself heartache in the future by saving files with next year's date with whatever changes I have made, so sometimes I find these time capsules of former versions. (And we won't talk about the feels of opening up files that pre-date my students date of birth.)
A lot of that growth from year to year is incremental, sometimes activities start out much smaller, sometimes as a single question. The first year I taught AP Physics C (2017) I wrote this warm-up question:
a. A block is suspended from a string; does the gravitational force do any work on it?
b. Explain how each could occur: i. gravitational force does positive work and ii. Gravitational force does negative work
There was immediate confusion and fierce debate so we started making and filling in a chart with some actual numbers:
I liked it so much I printed students their own copy of the chart the following year.
Thus it existed until 2021 when we were completely remote. With students known for copying each other in "zoom school," I made a different scenario (changed mass, displacement, acceleration, etc.) for each class in a slide deck. And I added questions I would normally ask in person. Here's
one such version and it's
key.
Now back in person, I continued with the slide deck for the longer activity, letting atudents work in pairs on it. The last few years I have also put small blocks on strings at each lab bench. Students tend to use it just like the gifs in the slide deck, raising it and lowering it as they discuss. Sometimes we review the answers in class, sometimes I spot check some questions after they submit it to Google Classroom.
This year I have a student teacher and while reviewing the activity with him, he was working through the same tricky parts as the students. The external work done by the force of tension is different than the "all potential energy becomes kinetic energy" examples they have done before with pendulums or a ball in free fall. To help him understand it, I found myself sketching energy bar charts, a strategy I don't usually use in AP but should.
So I made a new copy of the
slide deck for next year, and added a slide with a blank grid and boxes to manipulate to make into bars. Students will be abke oull the colored box up or down to fit the scale. Since there are four scenarios in the chart, I focused on just one. In the different versions between different classes I'll change which scenario they analyze.
I'm also adding questions asking them to use the acceleration and kinematics to find the final velocity after moving through that distance. Then they can find the change in kinetic energy and compare that to the net work done. I'm hoping by going back to more familiar calculations, they can confirm the calculations they do that day that seem contradictory.
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