Throwing and catching ball on a stability ball - with partner (Balance, sitting, throwing/catching ball with partner, on stability ball)

Sit on a stability ball, facing your partner whilst you hold a football between both hands
Place your feet firmly on the floor.
Find your neutral sitting posture and hold this position.
Throw the ball to your partner whilst keeping your balance.
Keep your balance as you catch the ball in return.
You can make this exercise more difficult by changing the direction of the throw.