Learning: You are in control of your own improvement

Everyone starts at the same time (preferably with a timer, but a clock or soundtrack does the trick too.) When you clap they have one minute to do as many of <technique/ukemis> as possible. The score is more important to yourself than the group, because you have a second chance to improve your own! 

Tip: Asking other students on how many they have performed makes them aware of the average. Letting the uke count is more fair than letting them count form themselves.