What a great positive group activity! Have one person sit on a chair in front of a white board while the others wrote a positive phrase about them. Take a picture to give to each person. A very creative and positive group activity.
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!