Lay the index cards vertically. Turn the cards to the blank side if they are lined on one side. Count out 26 cards--one for each letter of the alphabet.
Use a marker to write a 4-inch high uppercase letter "A" on of the blank side of the first card.
Turn the "A" card over and write a 2-inch high lowercase letter "a" on the back of the card.
Make one card for each of the remaining letters of the alphabet, writing the uppercase letter on the blank side and the lowercase letter on the lined side of each card.
Place a rubber band around the cards to store them between uses.