Had when i worked in a preschool and kids love them! I would use colored sand instead of white salt. DIY salt tray with alphabet cards. Easy to make and kids have fun smoothing out the salt after correctly making the letter
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!