I love the preschool idea of having a letter of the week. Here are some ideas for you to incorporate for the "A" letter of the week.
A is for Alligator
I love these alphabet craft ideas found at Totally Tots.
Turn an "A" into an alligator (made from craft foam).
Love this idea of making an alligator out of an egg carton.
FELT BOARD STORIES
5 Hungry "Alligators"
5 Little Monkeys (teasing Mr. Alligator)