I ordered a gears kit from School-Tech, hoping to have enough stuff for an entire class of kids to play with gears without taking apart the robot to scrounge up gears. Also, I figured I could add the gears to the robotics materials after the lesson was over. Unfortunately, the kit didn't arrive in time, but it turned out we had enough spare gears between the two robot kits for each group of 4 kids to have enough to play around with. I had them combine two gears with the same number of teeth, then combine a large and a small gear. They counted the number of rotations the small gear made for every rotation of the large gear. I pushed them to relate this to the number of teeth on each gear, and to make predictions about other combinations. They also observed the speed of the gears when combined in different ways. Easy and fun.
How much shortness of breath is too much?