Here’s the prompt:
Figure out where to hold the top of the spring so that when you release the mass, it just barely touches the floor at the bottom of the bounce. Once you have your plan started on a whiteboard, I will give tell you the spring constant and mass for your group.
It’s the end of our energy transfer packet, so we started this lab practicum last class. One group finished and tested their work successfully that day. Today, we spent some time letting others finish and test. That first group remade their whiteboard and presented to the rest of the class, then went around and helped here and there. Since each group had different numbers, they could work together on the process without being tempted to just see someone else’s result. The whole activity was for learning and fun, not a grade, so the stakes were low.
Here are a couple of the trials:
One of the interesting pieces for me in doing this activity with 9th graders was a new-for-me English/physics language problem—prediction. I meant that they should use physics to calculate a prediction; they heard “make a guess unrelated to the physics you put on your whiteboard” and that got some groups stuck for a little while as they tried to plug in their predictions and were confused by what their calculations meant.
There was also some difficulty in the math (good difficulties) and in recognizing how the stretch of the spring would relate to the initial height of the mass (another good difficulty). Would do it again. (Actually, will do it again in a few weeks with next trimester’s group.)