This is a great way to get your students working on letter and number strokes. I used an old clear picture frame box because it was free and it keeps the salt/sand from getting all over the place.
Clear Photo Frame
Double Sided Tape
For a rainbow background, cut your pieces in these dimensions. Lay the pieces evenly and secure with the double sided tape.
Place contact paper over the construction paper to keep the salt from going under the paper.
Spread the salt on top of the contact paper and have kids practice handwriting strokes.
Put the salt in a plastic bag and pack it all away by putting the back over the materials.