Begin with three players line up in a row about three yards apart. Two players are on the outside and one in the middle. The ball starts in the hands of a player on the outside.
Have multiple groups of players, so that you can make it competitive. The player on the outside tosses the ball to the player in the middle. That player then flicks the ball with his head to the third player behind him. The third player catches the ball. First to five wins, then switch the middle player. Ensure that all players have a turn in the middle.
You can add to this activity to increase the degree of difficulty. Instead of the third player catching the ball, he can head it back to the first. (Toss, flick on, head and catch). Rotate all players.
You can then move to toss, flick on, head, flick on again then catch. To simplify, player one tosses to player two. Player two flicks to player three, player three heads to player two, player two flicks to player one, player one catches. Again rotate all players, so everyone has a turn in the middle.
Continue to manipulate the activity to your liking. Remember to take into consideration the age and ability of the players.