This activity was originally a homework problem requiring a trip to a nearby park — there was one within a mile with a merry-go-round, which unfortunately no longer exists. The OSU Physics Department has since constructed a rotating chair with a flat platform attached.

I chose to spend 10 minutes at the beginning of class having (some) students experiment with the chair. This was fun for those who actually got to do it, but in 10 minutes that was only a couple of students. It's a bit hard to say whether the rest of the class got much out of it.

As class was beginning, I asked every student to attempt to draw a straight line on the rotating whiteboard and then had them do the full merry-go-round activity for homework. That seemed to go well. Having everyone attempt to draw a straight line meant that they were all primed to talk about what “straight” means when you start rotating.