Work in 2 teams each divided on one side of the field.
On each side there is also a chair starting on a position.
On this chair sits someone from the other team which makes sure that on the other side someone from your own team sits on a chair.
Other players serve the ball towards the chair. If the person sitting on the chair drops the ball, they switch positions and the chair moves one position.
Goal: be the first to move the chair around all positions and be back at the starting position.