Days 80-84: SHM Labs & Momentum Bar Charts

AP Physics 1: SHM Labs

We worked on labs to determine what affects the period of objects in simple harmonic motion. I had half the class experiment with pendulums, while half the class used springs. During the board meeting, we did a lot of jumping back and forth between the two experiments; this lead to some good discussion about energy when we saw that mass mattered for the springs, but not for pendulums. I had each spring group use a spring with a different spring constant, which also lead to some good discussion about why the pendulum groups all got the same slope on their linearized graphs, while each spring group got a different slope.

Physics: Momentum Bar Charts

This week, we developed conservation with cart explosions, then worked on using momentum bar charts to represent conservation of momentum problems. After last week, I spent some time talking about the purpose of giving students time to work all (or most) of the problems on paper and warned them I would be unhelpful when they were preparing their whiteboards, then held to it. When we got to mistakes whiteboarding, I required groups to make at least one of their mistakes in the bar charts. While students were working on paper and preparing their whiteboards, I saw a lot more small-group discussion than usual, both within groups and across groups, which was fantastic. During the whole-class discussion, I also got some students speaking up who are usually pretty quiet and one of my classes even got some really good student-to-student exchanges, which have been very rare this year. On Friday’s quiz, students consistently felt really good about their performance. I’m hoping that the positive experience students had whiteboarding these problems coupled with good performance on the quiz will move the class culture in the right direction.

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