There are several games I like to play with these cards. The first game I play with the students is a simple matching game. They have to match the uppercase letter to the lowercase letter. I tell the students that the Mama's and Papa's have find their little dears that fell out of the coconut tree, like in the book.
Once the students can proficiently match the uppercase letter to the lowercase letter, I use the cards in a center as a memory game. I usually start out by putting out a quarter of the alphabet to play with. The cards are laid out face down and the students take turn flipping two cards to find a match. As the students get the hang of the game, I add more letters for the to play with.
You can also use the letter cards as simple flash cards that go with the book Chicka Chicka Boom Boom. You can print out sets for each student so they can have their own letter cards to practice matching their upper and lowercase letters.