The court is covered with 20 cans of balls. Half of them are upside-down, and half are positioned the right way. 
The players are divided into two teams. One team is supposed to turn the cans the right way, and one team is to turn the cans upside-down.
At a command, the teams proceed to perform their respective task. 
After 1 minute, the coach yells “Stop!”; the team with the most cans turned in their favor wins.

Note: Good conditioning drill to use at the end of the class.