Move the Violet light across the Write and See Square and observe the brightly glowing trail. Violet light has enough energy to excite the phosphorescent pigment in the vinyl. The excited pigment then slowly releases energy as green light (the "glow" look). Red Light does not have enough energy to affect the pigment. Contains a mounted sheet of phosphorescent vinyl ~15 x 15 cm (6" x 6") and an incredible Violet Photon Light LED flashlight on a key-chain ring. Kindergarten through college, teach handwriting skills, or Albert Einstein's Photoelectric effect!!!