In order to develop the muscles of the body evenly, it is important for all of the major muscle groups be exercised.
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. )
this is called acquired immunity
