Feed the Alphabet Monster activity (Toddlers & Preschoolers at had a lot of fun with this! I also added a healthy "food" picture that coincided with each letter to "feed the alphabet monster".
For class word wall: A couple white sheets, a note sent home instructing mom to dress the kids in colorful clothes, and a ladder (and a photographer who is not afraid of heights! So fun! You could also do shapes.or spell out the name of the school!