Somewhere along the way kids learn the alphabet. It may be through your direct teaching, exposure to printed words, through games, or store signs, but sometime in their preK years you will realize they know their letters. I have noticed with my kids though that uppercase letters seem to be what they just learn on their own, and lowercase they need to be taught. I printed this sheet out from the PreKinders website and had Petie match some of our lowercase alphabet tiles to it's correct uppercase match on the sheet. He was able to do most of them on his own. The few he didn't know, I just had him look through some alphabet flashcards that have both cases together and he could find them that way. They also have sheets with the lowercase that you can match uppercase tiles too along with a ton of other alphabet activities. Check them out here.