Line-up players in groups of three. Set-up a rectangle 10-20 feet long and 5-10 feet wide. Place a player with a ball at each end of the rectangle. Station one player in the middle. Begin by having one of the players on the end pass the ball to the player in the middle. The player in the middle must return the ball immediately and then turn to receive a pass from the other player. Continue until the group has completed 5-10 passes to each side. You can make it competitive where the group to make 5 passes to each end first wins.