for warm ups go around the circle and get them each to say their favourite food, when everyone is done get them to hold their hands out and grab two handfulls of their favourite food and put it in the blender (grasp both hands together) and mix it all about (roll the wrists). To warm up their necks tell them to eat the food off their sholder, then the other sholder, then their stomach, then the roof, then tell them to wipe off the leftovers off of their shoulders and stomach and roof. for the straddle (warm up of the legs) get them to put their hands behind their back and go in a semi circle eating their favourite foods. These exercises are great because it teaches you more about the gymnast (their favourite food) and also makes it fun to warm up. As for games get them all to stand on the beam in a line and hold hands, give one of the end gymnasts a hoop and they have to get it to the other side without letting go, increase the difficulty with a hoop on each end (two hoops) and gradually add up more, it gets dificult because they need to remember what colours they started with in order to cross over and go the right way. Also get the gymnasts to stand up on the beam and you throw them a ball and they have to catch (try pretending to throw it to another person to trick them), if they fall they are out, it teaches them balance too which is why most games are good to be played on the beams, add in a clap before catching the ball etc. Good luck