Writing with Carrots? Why Not? dip it in veggie dip onto black papper. Or a banana (dipped in pudding? (I haven't figured out how to use A's fav: Seaweed . Large letters though. lots of space for these fun ideas!
OMGGGG Make, explore and paint rainbows. Use a CD and sunlight or a flashlight to cast rainbows, study and paint with watercolors or color with markers or crayons. A great piece of process art for kids. Art and science, STEAM projects for preschoolers.