A good warm-up to use before a match and to improve ground ball skills.
Two players on the same side of the grid sprint to the opposite corner. They place the ball 2 metres away from the opposite player making sure they place it securely so it does not roll. Then they join the back of the queue. The next player runs out and picks up the ball quickly but carefully to avoid a knock-on and sprints to the opposite corner.
See Passing Square, Rolling Square, Left/Right Pass Square. At one edge of the grid, a pop pass can be made instead of placing down the ball.