We have our kids sometimes play a game called Green and Grey. We split the class in half and have them line up facing each other, starting maybe 10' appart. One team is green, the other is grey. They each have a line about 20' behind them which is their safe line. When the instructor calls a colour, that team has to try and tag members of the other team before they can turn and run back to their own safe line (eg if GREY is called, GREEN will turn around and run away while GREY chases them). If you are tagged you are eliminated and sit out. Also, if your team's colour is called and you take more than one step away from the other team you are eliminated. That is to prevent people from just turning and running whenever any colour is called. As the game progresses, we have them get closer together until they are standing back to back only about a foot appart. Sometimes we'll also have them laying down in push-up position before the colour is called, or sitting back to back. The kids love that one!