The player with the ball tosses the ball to another player and remembers that player because in subsequent rounds that player will toss it to the same player each time.

Once a player receives a ball they might put their hand up indicating that they have already received and tossed a ball.

Once the group succeeds at passing the ball through the group, they can add a second ball, and then another, and another, until everyone has a ball and they all toss and receive at the same time.