Use the circle with channels. Ball 1 = 1v1 Ball 2 = 2v3 Ball 3 = 3v4 Ball 4 = 4v4

Working on defending as the primary component with trying to defend outside the circle as to not give away PC's. Identifying when have a man advantage and can play zone and be more aggressive vs equal numbers and have to play Man v Man.

You wouldn't really extend this exercise. All you could do is change who gets the advantage. e.g. more attackers than defenders.