18 Halloween Science Experiments for Kids That Fizz & Glow!
What if the spookiest thing in your house this October wasn't the plastic skeleton on the porch, but the bubbling, glowing, oozing concoctions on your kitchen table? Halloween science experiments turn a regular afternoon into a mad-scientist lab, and kids learn real chemistry and physics without even noticing they're learning.
We rounded up 18 easy Halloween science experiments for kids that use things you probably already have: baking soda, vinegar, candy, cornstarch, balloons, and a pumpkin or two. For each one, we included ages, time, mess level, a supply list, quick steps, and a kid-friendly explanation of the science, checked against trusted educational sources like Science Buddies, the American Association of Chemistry Teachers, and The Franklin Institute.
Before You Start: Safety Rules for Little Mad Scientists
Every experiment on this list is meant to be done with an adult nearby. Most are gentle, but "gentle" and "a four-year-old holding a cup of vinegar" don't always go together. Set up on a tray, a baking sheet, or outside on the patio, and keep paper towels within arm's reach.
Here are the ground rules we use at home:
Wear safety glasses or swim goggles for anything that fizzes, foams, or splashes. Vinegar and hydrogen peroxide sting if they get in your eyes.
Nothing gets tasted unless a grown-up says it's food. Experiment candy is for science, not snacking.
Check candy labels for allergens, and swap in allergy-friendly treats when friends join the fun.
Use latex-free balloons if anyone in the house has a latex allergy.
Grown-ups handle knives, hot water, and anything with a warning label.
Wash hands when you're done, especially after touching raw eggs.
Parent tip: Give kids a "lab notebook" (a stapled stack of paper works fine) and ask them to draw what they think will happen before each experiment. Predicting first is what makes it science instead of just a mess.
Bubbly, Fizzy Halloween Science Experiments
Acid-base reactions are the superstars of Halloween science experiments. Mix an acid (like vinegar or lemon juice) with a base (like baking soda) and you get carbon dioxide gas, which means bubbles, foam, and very happy kids.
1. Erupting Pumpkin Volcano
Ages: 3 and up (adult does the carving)
Time: 15 minutes
Mess level: High (do it outside or in a big tray)
You'll need: A small pumpkin, 1/4 cup baking soda, 1 cup vinegar, a squirt of dish soap, orange or green food coloring
Nothing says "Halloween lab" like a jack-o'-lantern that foams at the mouth. It's the classic baking soda volcano wearing a costume.
An adult cuts the top off a small pumpkin and scoops out the seeds (save them for roasting).
Add baking soda, a squirt of dish soap, and a few drops of food coloring inside.
Pour in vinegar and step back while the pumpkin oozes foam out of its mouth and eyes.
Add more baking soda and vinegar for round two.
The science: Vinegar contains acetic acid, and baking soda is a base called sodium bicarbonate. When they meet, they react and make carbon dioxide gas, water, and a salt. The gas bubbles are trapped by the dish soap, which turns the fizz into thick foam. The American Association of Chemistry Teachers explains this reaction in their balloon demo.
2. Self-Inflating Ghost Balloons
Ages: 4 and up
Time: 10 minutes
Mess level: Low
You'll need: White balloons, a black marker, an empty plastic bottle, baking soda, vinegar, a funnel
This one feels like a magic trick. Your ghost literally puffs itself up with no huffing required.
Draw a ghost face on a white balloon and let the marker dry.
Use a funnel to put about two teaspoons of baking soda inside the balloon.
Pour about 1/2 cup of vinegar into the bottle.
Stretch the balloon over the bottle's mouth, then lift it so the baking soda falls in. Watch your ghost rise.
The science: It's the same fizzy reaction as the pumpkin volcano, but this time the carbon dioxide has nowhere to go except into the balloon. More gas means more pressure, and more pressure means a bigger ghost.
Parent tip: Turn it into a real experiment by testing different amounts of baking soda. Which ghost gets the biggest?
3. Witch's Lava Lamp
Ages: 5 and up
Time: 15 minutes
Mess level: Medium
You'll need: A clear bottle or jar, water, vegetable oil, food coloring, an effervescent antacid tablet (like Alka-Seltzer)
Bubbling blobs of green or orange "potion" rise and fall like a spooky lava lamp. Dim the lights and shine a flashlight underneath for maximum drama.
Fill the jar about one-quarter with water and add several drops of food coloring.
Fill most of the rest with vegetable oil and wait for the layers to separate.
Drop in a piece of an antacid tablet and watch the colored blobs bubble up.
Add another piece when the bubbling slows down.
The science: Oil and water don't mix, and oil floats on top because it's less dense. The tablet reacts with water to make carbon dioxide gas bubbles, which carry colored water up through the oil. At the top, the gas escapes and the heavier water sinks back down. Science Buddies' lava lamp activity shows that warm water makes it bubble faster and cold water makes it calmer and longer-lasting.
Parent tip: Don't pour the oil down the drain. Put it in the trash in a sealed container so it doesn't clog your pipes.
4. Monster Foam (Kid-Safe Elephant Toothpaste)
Ages: 6 and up (adult pours the peroxide)
Time: 15 minutes
Mess level: High
You'll need: 1/2 cup 3% hydrogen peroxide (the drugstore kind), dish soap, food coloring, 1 packet dry yeast, warm water, an empty plastic bottle, safety glasses, a tray
A tower of warm, colorful foam comes pouring out of a bottle like a monster that can't stop drooling. Kids will ask to do this one again. And again.
Put on safety glasses and set the bottle in a tray or outside.
Pour in the hydrogen peroxide, a good squirt of dish soap, and a few drops of food coloring.
In a separate cup, mix the yeast with a few tablespoons of warm water.
Pour the yeast mixture into the bottle and step back.
The science: Yeast contains an enzyme called catalase that speeds up the breakdown of hydrogen peroxide into water and oxygen gas. The dish soap traps the oxygen in bubbles, making foam. The bottle feels warm because this reaction gives off heat. Science Buddies' elephant toothpaste guide notes that safety glasses are a must, and stronger peroxide should never be used without protective gear and an adult.
Pumpkin Science Experiments
Pumpkins aren't just for carving. That big orange squash is a floating, rotting, surprisingly scientific specimen, and it's the star of some of our favorite pumpkin science experiments.
5. Will It Float? Pumpkin Edition
Ages: 3 and up
Time: 10 to 15 minutes
Mess level: Medium (splashy)
You'll need: A bathtub, big bin, or kiddie pool; pumpkins and gourds of different sizes; a small apple and a rock for comparison
Ask your kids: will a giant pumpkin sink or float? Most of them will guess "sink" because it's so heavy. Then let them find out.
Have kids predict sink or float for each item and write it down.
Gently place each pumpkin, gourd, apple, and rock in the water.
Compare the results to their guesses.
Bonus: carve one pumpkin open and test the lid, a chunk of flesh, and a few seeds.
The science: Whether something floats depends on density, or how much "stuff" is packed into its size, not just how heavy it is. A pumpkin is mostly hollow and filled with air, so its overall density is lower than water and it floats. A small rock is packed solid, so it sinks.
6. Rotting Pumpkin Jack Decomposition Lab
Ages: 4 and up
Time: 5 minutes to set up, then a few weeks of observing
Mess level: Low (if you keep it outside)
You'll need: A carved pumpkin after Halloween, a spot in the yard or garden, a phone for photos
This is the gross-out experiment that keeps giving. Instead of tossing your jack-o'-lantern on November 1, let your kids watch it collapse into the dirt.
Place the old jack-o'-lantern in a garden bed or a corner of the yard.
Take a photo from the same spot every few days.
Ask kids to describe what they see: fuzzy mold, shrinking, collapsing, bugs.
After a few weeks, check whether any seeds sprout.
The science: Mold, bacteria, and small critters are decomposers. They break down the pumpkin and return nutrients to the soil, which can help new plants grow. The NC State Extension 4-H "Pumpkin Jack" project tracked a pumpkin's weekly breakdown into soil and then watched to see if it would sprout.
Parent tip: Mold spores can bother people with allergies or asthma, so observe with eyes only and keep the pumpkin outdoors.
Candy Science Experiments
Got a mountain of candy? Science is the perfect excuse to "use it up" before your kids eat all of it. For more ideas, see our list of creative ideas for leftover Halloween candy.
7. Dissolving Candy Corn Race
Ages: 4 and up
Time: 20 to 30 minutes
Mess level: Low
You'll need: Candy corn, gummy candies, clear cups, cold water, warm tap water, a timer
Which disappears faster, candy corn in cold water or warm water? And what happens to gummies? The results surprise a lot of kids.
Fill one cup with cold water and one with warm tap water.
Drop the same number of candy corns into each cup and start the timer.
Repeat with gummy candies in two more cups.
Check every five minutes and compare.
The science: Candy corn is mostly sugar, and sugar dissolves in water. Warm water molecules move faster, so they break the sugar apart more quickly. Gummies are different: they're made with gelatin, so in cold water they soak up water and swell instead of dissolving. Science Buddies' candy melt activity explains both reactions.
8. Candy Rainbow Chromatography
Ages: 6 and up
Time: 30 minutes
Mess level: Low
You'll need: Colorful candy-coated candies (like Skittles or M&M's), coffee filters, cups of water, a toothpick or paintbrush, a pencil
Is an orange candy really just orange? Paper chromatography lets kids "unmix" candy colors and discover hidden dyes.
Cut coffee filters into strips and draw a pencil line near the bottom.
Wet a candy, then dab its color onto the pencil line.
Stand the strip in a cup with just a little water, keeping the dot above the water.
Watch as the water climbs and the colors separate.
The science: Candy colors are made of dyes, and some colors are a mix of more than one. As water moves up the paper, each dye travels at a different speed, so the mixed colors spread apart into separate bands. Science Buddies' candy chromatography post challenges kids to compare whether the same color from different brands uses the same dyes.
9. Candy Corn Geodesic Dome Challenge
Ages: 5 and up
Time: 30 to 45 minutes
Mess level: Low
You'll need: Gumdrops or candy pumpkins, toothpicks, a small book for weight testing
This is engineering disguised as snack time. Kids build a dome out of triangles and see how much weight it can hold.
Push toothpicks into gumdrops to make triangles.
Connect the triangles into a dome shape.
Build a cube out of squares for comparison.
Gently stack small books or toys on each and see which one holds more.
The science: Triangles are rigid shapes that don't easily bend out of shape, while squares can squish sideways. A dome built from lots of triangles spreads weight out evenly. Science Buddies' geodesic dome project explains why engineers love this design.
Parent tip: Little ones and toothpicks need close supervision. For toddlers, use jumbo marshmallows and pretzel sticks instead.
Oozy, Slimy, and Gross Halloween STEM Activities
Some kids want pretty colors. Other kids want goo. These Halloween STEM activities are for the goo crowd.
10. Monster Oobleck
Ages: 2 and up (with close supervision)
Time: 10 minutes to make, endless minutes to play
Mess level: High
You'll need: Cornstarch, water, a bowl, green food coloring, plastic spiders or eyeballs (optional)
Is it a liquid or a solid? Oobleck is both, and it's one of the best sensory science activities for little kids.
Pour cornstarch into a bowl and add a few drops of green food coloring to the water.
Add water a little at a time, stirring as you go, until the mixture is thick and gooey (roughly two parts cornstarch to one part water).
Punch it fast, then let your hand sink in slowly.
Hide plastic spiders inside for a "swamp monster" dig.
The science: Oobleck is a non-Newtonian fluid. When you press or squeeze it hard, the cornstarch particles jam together and it acts like a solid. When you move slowly, it flows like a liquid. Science Buddies' oobleck activity explains that cornstarch particles stay suspended in the water instead of dissolving.
Parent tip: Never pour oobleck down the sink. It can clog pipes. Let it dry out and throw it in the trash.
11. Spooky Fake Blood Viscosity Test
Ages: 6 and up
Time: 20 minutes
Mess level: Medium (can stain)
You'll need: Corn syrup, water, red and a touch of blue food coloring, cocoa powder or cornstarch, spoons, a tilted plate or cutting board
Costume makeup meets physics. Kids mix different batches of pretend blood and race them down a ramp to see which drips most realistically.
Make three small batches: corn syrup plus coloring, water plus coloring, and corn syrup plus coloring and a spoon of cocoa or cornstarch.
Put a spoonful of each at the top of a tilted plate.
Watch which one oozes slowest and which one runs fastest.
Decide which looks most like movie blood.
The science: Viscosity is how thick a liquid is and how easily it flows. Water has low viscosity, so it zooms. Corn syrup has high viscosity, so it oozes. Science Buddies' physics of fake blood post explains how special-effects artists use viscosity to make fake blood look real.
Parent tip: Food coloring can stain clothes and grout. Wear old shirts and work on a washable surface.
12. Monster Eyeball (Naked Egg)
Ages: 5 and up
Time: 10 minutes to set up, 1 to 2 days of waiting
Mess level: Low (until someone drops it)
You'll need: A raw egg, white vinegar, a clear jar, a spoon
After a day or two in vinegar, a raw egg loses its shell and turns into a bouncy, see-through "eyeball." It's creepy in the best way.
Put a raw egg in a jar and cover it with vinegar.
Watch tiny bubbles form on the shell.
After about 24 to 48 hours, gently rinse off any leftover shell.
Hold it up to a flashlight and gently bounce it an inch above a plate.
The science: Eggshells are made of calcium carbonate. The acetic acid in vinegar dissolves the shell and releases carbon dioxide bubbles. What's left is the egg's thin, rubbery membrane. Science World's naked egg activity walks through the acid-base reaction.
Parent tip: It's still a raw egg, so wash hands after touching it and don't let anyone eat it.
Light, Static, and Shadow Experiments
These Halloween science experiments are perfect for the evening, when it's dark enough for glowing potions and dancing shadows.
13. Glowing Potion (Tonic Water Under a Blacklight)
Ages: 4 and up
Time: 10 minutes
Mess level: Low
You'll need: Tonic water (the kind with quinine), plain water, clear cups, a UV blacklight or blacklight flashlight
Turn off the lights, switch on a blacklight, and the tonic water suddenly glows an eerie blue. Regular water sitting right next to it? Nothing.
Pour tonic water into one clear cup and plain water into another.
Darken the room and shine the blacklight on both.
Compare the glow.
Try other things around the house under the light, like white T-shirts or highlighters.
The science: Tonic water contains quinine, which absorbs invisible ultraviolet light from the blacklight and gives off visible blue light. That's called fluorescence. Science Buddies' glowing tonic water activity also warns to avoid shining UV light directly into eyes or onto skin.
14. Dancing Tissue Ghosts
Ages: 3 and up
Time: 10 minutes
Mess level: Low
You'll need: A balloon, tissue paper, scissors, a marker, a wool sweater or your hair
Kids make tiny ghosts leap up and "dance" without touching them. It looks like magic, but it's static electricity.
Cut small ghost shapes out of tissue paper and draw faces on them.
Lay the ghosts flat on a table.
Blow up a balloon and rub it on your hair or a sweater for about 20 seconds.
Hold the balloon just above the ghosts and watch them jump up to meet it.
The science: Rubbing the balloon pulls tiny particles called electrons from your hair onto the balloon, giving it a negative charge. Opposite charges attract, so the lightweight ghosts leap toward the balloon. The Franklin Institute's static electricity activity explains how like charges repel and opposite charges attract.
Parent tip: Static works best on dry days. Luckily, LA's fall weather is usually very cooperative.
15. Monster Shadow Puppet Theater
Ages: 3 and up
Time: 30 minutes
Mess level: Low
You'll need: Cardstock, scissors, craft sticks, tape, a flashlight, a blank wall
Build bats, ghosts, and witches, then put on a show and learn how light makes shadows.
Draw and cut out Halloween characters from cardstock.
Tape each one to a craft stick.
Set a flashlight on a box pointing at a blank wall and turn off the lights.
Move the puppets closer to and farther from the light and watch what happens.
The science: Light travels in straight lines, and a shadow forms where an object blocks it. The closer the puppet is to the flashlight, the more light it blocks, so the shadow grows giant and scary. Science Buddies' shadow puppet activity has kids test how distance and angle change shadows.
More Easy Halloween STEM Activities
16. Magic Potion Swirl (Milk Rainbow)
Ages: 3 and up
Time: 10 minutes
Mess level: Low
You'll need: Milk (2% or whole works best), a shallow plate, food coloring, dish soap, cotton swabs
Call it a witch's potion. Drop colors in milk, touch it with a soapy swab, and watch the colors explode into swirls.
Pour milk into a plate to cover the bottom.
Add drops of purple, green, and orange food coloring near the center.
Touch a plain cotton swab to the milk first (nothing happens).
Dip the swab in dish soap and touch the same spot. Whoosh.
The science: Dish soap lowers the surface tension of the milk where it touches, and the soap molecules grab onto the fat in the milk. That makes the milk and colors rush away from the swab. Science Buddies' milk rainbow activity explains why the swirling stops once the soap spreads everywhere.
17. Spider Web Engineering Challenge
Ages: 4 and up
Time: 20 to 30 minutes
Mess level: Low
You'll need: Painter's tape or yarn, a doorway, cotton balls or plastic spiders, a timer
Can your kids build a web strong enough to catch "flies"? This one gets them moving and problem-solving.
Stretch strips of painter's tape (sticky side facing out) or yarn across a doorway to make a web.
Stand back a few steps and toss cotton balls at it.
Count how many stick.
Redesign the web with more crossing lines or a different shape and test again.
The science: This is an engineering design challenge: build, test, improve, and test again. Webs with more crossing strands have more places for "prey" to stick, which is why real orb-weaver spiders build webs with lots of spiral lines.
Parent tip: Painter's tape comes off door frames more easily than regular tape and won't peel your paint.
18. Bubbling Witch's Brew With Dry Ice (Grown-Up Demo Only)
Ages: Kids watch; adults handle everything
Time: 10 minutes
Mess level: Low
You'll need: Dry ice (from a grocery store or dry ice supplier), insulated gloves and tongs, a sturdy open bowl or cauldron, warm water
A cauldron spilling spooky fog is the showstopper of Halloween science experiments. It's also the one that needs the strictest rules, so this is a grown-up demonstration only. If you're not comfortable with every rule below, skip it.
An adult wears insulated gloves and uses tongs to place a few chunks of dry ice into warm water in an open bowl.
Kids watch from a safe distance as the fog rolls out.
Keep the bowl in a well-ventilated room or outdoors.
Never let kids touch, taste, or hold dry ice.
The science: Dry ice is frozen carbon dioxide. It doesn't melt into a liquid; it turns straight into gas, which is called sublimation. The cold gas chills the moist air above the water into a thick fog. Cornell University's dry ice safety guidance notes that dry ice is about -109°F and can cause freezing injuries, that it should only be used in well-ventilated areas, and that it must never be placed in a sealed container because the gas can build up pressure and burst it. Never put dry ice in drinks.
Where to Find Spooky Science Fun Around LA This October
Want someone else to handle the cleanup? A few Los Angeles-area museums are serving up Halloween fun with a side of science this fall. Here's what we confirmed on official pages for 2026. For even more ideas, browse our 89 Best Family-Friendly Halloween Events in Los Angeles.
11800 Foothill Blvd.
Sylmar, CA 91342
Now through Sunday, November 8, 2026
10 a.m. to 5 p.m.
This year's Enchanted Halloween mixes science and magic, with a Magician's Workshop where kids learn three tricks, famous illusion displays, a haybale maze, a corn maze, pumpkin catapults, tractor trails, and a Día de los Muertos ofrenda. Trick-or-treat stations run on weekends only, and every guest gets a reusable trick-or-treat bag.
It's included with general admission or membership. Ticket prices weren't listed on the event page, so please check the official Discovery Cube website before you go. The museum's parking lot is entered from Dronfield Ave. off Osborne St.
Parent tip: Young magicians perform on select weekend days through November 8. Check the event page for the schedule and plan your visit around a show.
480 N. Arroyo Blvd.
Pasadena, CA 91103
Now through Saturday, October 31, 2026
Tuesday to Sunday, 10 a.m. to 5 p.m.
Kidspace's Halloween season is made for little ones, with costume parades every day at 11 a.m., 1 p.m., and 3 p.m., potion-mixing in the Witch's Kitchen, an Adopt-a-Monster design station, and pumpkin bowling. There's a LEGO Monster Build on October 3 and 4, and a daytime Halloween party on October 31 with a parade, face painting, and balloon twisters.
Everything is free with Kidspace admission, which is $17 for adults and children ages 1 and up, $15 for seniors 62 and up, and free for infants and members. Kidspace doesn't accept cash, so bring a card.
Parent tip: The potion-making in the Witch's Kitchen is a great warm-up before you try the milk swirl or glowing potion experiments at home.
900 Exposition Blvd.
Los Angeles, CA 90007
Saturday, October 10, 2026
5 p.m. to 9 p.m.
This one-night after-hours event is open to all ages and includes the museum's Orcas: Our Shared Future exhibition, scientist encounters about nocturnal animals, dancing, and food trucks with food for purchase.
Tickets are $50 for adults 18 and up and $30 for kids ages 3 to 17 for nonmembers and Individual/Family members. Children 2 and under are free, and some higher membership levels include free tickets. Check NHM's website for parking details.
700 Exposition Park Dr.
Los Angeles, CA 90037
We didn't find special Halloween programming announced for 2026, but general admission to the permanent exhibit galleries is free (IMAX and special exhibits cost extra). It's right next door to NHM, so it pairs nicely with a Haunted Museum evening or a free weekday science outing. Check the official website for current hours and any timed-entry reservations.
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Takeaway
You don't need a lab coat or fancy kit to pull off memorable Halloween science experiments. A box of baking soda, a jug of vinegar, some cornstarch, and a bag of candy can fill an entire October of fizzing, glowing, and oozing fun.
Start with the easy wins, like the pumpkin volcano, dancing ghosts, and oobleck, and work up to monster foam and candy chromatography for older kids. Keep the goggles on, keep a grown-up close, and let your kids ask "What will happen if...?" as many times as they want. When your pumpkins finally retire, try our no-carve pumpkin decorating ideas next year and turn this year's jack-o'-lantern into a decomposition lab. And before the big night, brush up on our trick-or-treat safety tips.
Halloween Science Experiments FAQs
What are the easiest Halloween science experiments for preschoolers?
Oobleck, dancing tissue ghosts, the milk potion swirl, sink-or-float pumpkins, and the erupting pumpkin volcano are the best picks for ages 3 to 5. They use simple supplies, work quickly, and don't require reading or careful measuring. An adult should still supervise every step.
What household supplies do I need for Halloween STEM activities?
Most of these experiments use baking soda, white vinegar, dish soap, food coloring, cornstarch, balloons, clear cups, coffee filters, milk, and leftover candy. A small pumpkin, a flashlight, and a pair of safety glasses or swim goggles cover almost everything else.
Are Halloween science experiments safe for kids with food allergies?
They can be, with a little planning. Read candy labels carefully, choose allergy-friendly candy for chromatography and dissolving experiments, use latex-free balloons if needed, and remind kids that experiment materials are never for eating. When friends with allergies join in, ask their parents what's safe.
Is dry ice safe to use in a Halloween science experiment with kids?
Only as an adult-handled demonstration. Dry ice is about -109°F and can freeze skin, so adults should use insulated gloves and tongs, keep it in an open container in a well-ventilated area, and never seal it in a jar or bottle. Kids should watch from a distance and never touch or taste it.
How do I turn a Halloween experiment into a real science lesson?
Ask your child to predict what will happen, change just one thing at a time (like warm water versus cold), and record the results with drawings or photos. Then talk about why it happened. That simple predict-test-explain routine is the heart of the scientific method, and it works for kids of every age.
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