A hand closes around the glowing goo and, for one strange second, it feels solid. Then the fingers open. The whole handful loosens, slips between them, and pours back into the bin. That is the trick hiding inside oobleck. Push it and it pushes back. Hold still and it melts away. Turn out the lights and the whole experiment becomes goblin goo. Plastic spiders disappear beneath the surface. Eyeballs sink slowly. Little hands keep reaching back in to find them. Looking for more ways to play after dark? Visit our Glow in the Dark Activities collection. For pumpkins, ghosts, sensory play, and Halloween science, step into our Halloween Activities for Kids collection . What You Need Cornstarch Tonic water with quinine A shallow bin or large bowl A spoon for the first stir Washable Halloween toys, such as plastic spiders, eyeballs, skeletons, or mini pumpkins A black light, optional for the glowing effect A two-to-one ratio is the easiest place to begin. For a generous sensory bi...