My grands LOVE sorting my buttons. I give them a pipe cleaner and they string like ones together.
How about letting them sort your scraps into ziplock bags by color. Then they can take any that they like and make a pillow.
They can draw a picture or trace it out of a coloring book and trace it onto 1/2" pine. Then have someone cut it out for them. They can sand it, paint it, and bring it home to put in their room or the garden.