Letter ID Cereal Box - Spread out lowercase letters on fish and have kids pick up an upper case letter from a stack. They have to find the lowercase letter that corresponds to the uppercase letter and feed the penguin. I've also seen this to match pictures to their beginning sound
Also on these boards
match upper and lowercase and first letter sound pictures!
Match upper and lowercase letters with this playdough activity.
a fun activity to practice matching uppercase and lowercase letters
Uppercase to lowercase letter matching with Unifix cubes