Group Activity Cards
Geometry
Number of players: 2
Materials: Spinners

Master Cylinders 
Label equal sections of two spinners "2," "3," "4," "5," "6," "7." Decide which spinner you want to stand for the height of a cylinder and which spinner you want to stand for the radius of a cylinder's base. (You and your partner must choose differently.)
Each partner spins a spinner. Then both partners compute the surface area for a cylinder with the resulting height and radius of a base. The partner with the greater surface area wins the round. Play five rounds, comparing your results each time.
Suppose the spinners were labeled with different numbers. Is there a way to determine the winner of the round without actually calculating the surface areas?
