Pair-up and give each a ball and mark out a 5m x 3m rectangle.
(A) always passes diagonally , (B) always passes up the line.
(A) passes from: (1 to 2) & (3 to 4)
(B) passes from: (2 to 3) & (4 to 1)
On 'go!', (A) passes diagonally across the square to (B) on (2), then runs to (3)
(B) passes to (A) on (3), then runs to (4)
(A) passes diagonally to (B) on (4), then runs back to (1)
The loop is completed when (B) passes to (A) on (1), before returning to (2).
