Magic Cauldron DIY
This Halloween science experiment for kids turns a sheet protector, vegetable oil, and a paper towel into a cauldron that gulps down drops of green potion. Drag each drop across the slick plastic with a stick and watch your cauldron slurp it up the second it touches the rim.
Materials you’ll need
- white paper
- black marker
- clear sheet protector
- paper towels
- scissors
- vegetable oil
- glass of water
- green food coloring
- dropper
- wooden stick
Step-by-step tutorial
Step 1: Grab a black marker and draw a big, round witch’s cauldron on a sheet of white paper.Step 2: Slide your cauldron drawing into a clear sheet protector.
Step 3: Cut a paper towel to fit inside your cauldron outline. Lay it on top of the sheet protector, right inside the lines, and press it flat.
Step 4: Pour 1 tablespoon of vegetable oil onto the plastic above your cauldron. Use a second paper towel to wipe the oil across the plastic until it’s coated in a thin, slick layer.
Step 5: Brew your potion by stirring a few drops of green food coloring into a glass of water. Use a dropper to drip little potion drops all over the plastic above the cauldron.
Step 6: Touch a wooden stick to a potion drop and drag it toward the cauldron. When the drop reaches the paper towel, your cauldron gulps it right down.
Learn more
This spooky cauldron comes from two of water’s sticky superpowers: cohesion and adhesion. Water molecules pull on each other (cohesion) much more than they stick to oily plastic, so each potion drop holds together in a round bead instead of spreading out. Water also sticks to some other materials (adhesion), like the wood of your stick, so the drop tags along when you drag it. When a drop touches the paper towel, the water sticks to the towel’s fibers even more than it sticks to itself, and capillary action pulls it into the tiny gaps between the fibers.If your cauldron was a hit, the Light-Up Haunted House takes Halloween science further with LEDs and a battery-powered build that makes its vellum paper windows glow.