Set out 2 grids that are attached by a common line with 3 attackers and 1 defender in each and an extra defender who is allowed to move into whichever grid has the ball.
3 Players, with one ball, in one grid keep possession of the ball and try to pass the ball to the other three players in the other grid.
Once they have done this the other three players must also try to keep possession in order to once again pass the ball back into the other grid.
To keep possession the players should pass the ball quickly.
Switching areas as often as possible to make the floating defender run as much as possible.