Halloween · STEM
15 Halloween Science Experiments for Kids
Bubbling cauldrons, dancing ghosts and pumpkin experiments that sneak a little science into spooky season.
Halloween is perfect for science because ordinary reactions already look like magic. The trick is to let kids predict what will happen before the “potion” starts fizzing.
Most of these use common household materials, but adults should supervise every experiment and take over completely for anything involving heat, fire, sharp tools or small choking hazards.
15 spooky STEM experiments
Turn each activity into real science by making a prediction and changing only one thing at a time.
Bubbling Witch’s Cauldron
Add baking soda to a bowl, tint it with food coloring, then pour in vinegar and watch the foamy “potion” rise. Use a tray underneath.
Dancing Ghosts with Static
Cut tiny ghosts from tissue paper. Rub a balloon on hair or fabric, then hold it near the ghosts to make them lift and dance.
Pumpkin Volcano
Carve or hollow a small pumpkin, add baking soda and dish soap inside, then pour in vinegar for an overflowing eruption.
Magic Milk Monster Colors
Add drops of food coloring to milk, then touch the surface with a cotton swab dipped in dish soap to send colors swirling.
Oobleck Monster Slime
Mix cornstarch and water until it behaves like a solid when squeezed and a liquid when released. Tint it green if desired.
Floating Ghost Teabag
With close adult supervision, an empty upright tea-bag paper tube can be lit at the top and may rise as the hot air lifts the ash. This one is adult-demo only and should be done on a fire-safe surface.
Candy Corn Density Test
Drop candy corn or other Halloween candy into water, oil and other safe household liquids and compare whether pieces sink, float or dissolve.
Pumpkin Sink-or-Float
Predict whether different pumpkins and gourds will float in a tub of water, then test them.
Glow Stick Temperature Test
Place activated glow sticks in cold, room-temperature and warm water and compare how bright they appear.
Spider Web Strength Test
Build webs from yarn, tape or string between two supports, then test how many small toy spiders or clothespins each design can hold.
Ghost Balloon Inflation
Put baking soda in a balloon and vinegar in a bottle. Attach the balloon without spilling, then lift it so the powder falls in and the gas inflates the “ghost.”
Dissolving Candy Experiment
Place the same kind of candy in cups of different liquids and observe changes in color, size and texture over time.
Pumpkin Decomposition Journal
Put a small pumpkin outside in a safe spot and photograph or sketch it every few days as it changes.
Magnetic Monster Maze
Draw a maze on cardboard, place a paper-clip monster on top and move it through the maze using a magnet underneath.
Fizzing Eyeballs
Freeze small baking-soda balls with plastic eyes inside, then drip vinegar over them to fizz the “eyeballs” free.