1. Make sure the sport they are playing, that the item can't cause a real injury 2. Make sure the surrounding area is acceptable so like no slippery floor, or marble floor 3. Make sure every kid is doing the steps correctly or game, if not, then teach them and separate from kids doing good.
( I don't know if you meant ruled steps, so I made some, this is just what I think, hope it's what you want. )
A student is trying to reach a goal, that goal is to get good grades. If I wanted to get a phone for working hard in school, it would then be an incentive.