Each participant gets a ball and stands in a line facing a gym wall so that each participant is about 10 feet away from the wall.
After a signal, each participant throws their ball against the wall but have to catch a DIFFERENT ball than the one that they threw. Behind them stand two catchers (you can start with the facilitators being the catchers if you wish), who try to get any of the balls.
Whoever has not caught a ball is out, and joins up with the catchers. Eventually, there is just one player who has a ball (or it is tied).
This game can get quite disorderly at the end as the catchers are all trying to stop the final participant from getting a ball.