Have you class get in a big circle. Give them directions on what to do with their legs. For example, jog or jack. Then toss a ball in and have them pass it round. You could have then hit it or throw it. I sometimes have them call out names. Set some rules ilke no stopping your feet or saying sorry when you dont catch the ball. Keep tossing in balls so they have more then one going at a time. Everyone loves this.