Use a marker to write numbers (0-9) on two sides of the balls you use during hitting drills. Players must pick up the number on the ball before they hit it. For an added challenge you can also write numbers in either red or black. Write each number in both colors on different balls. Otherwise players will remember that 5 is red, or that 3 is black. Each number should appear in red on some balls and in black on others.
Simple - Pick up just the color
Medium - Pick up just the number
Harder - Pick up the number and color
Hardest - Increase the speed of the pitch and have batters pick up both the number and color