Put 4 hats in a square and 1 hat with a tennis ball in the middle, the distance between the hats is 5 meters.
Start running at an empty hat and take the tennis ball from the middle hat and put it on an empty hat on the outside.
Then run to the middle again and tap the hat in the middle with your hand, Â then run to the hat with the tennis ball and pick it up and put it on the hat in the middle.
You run through all the hats and then give the tennis ball to the next runner who does the same.