Halloween Science Experiments and STEM Activities for Kids

Halloween science experiments are the perfect mix of spooky fun and hands-on learning. From erupting pumpkins to ghostly balloons, kids can explore chemistry, physics, and biology with simple supplies. These activities work for classrooms, homeschool, or after-school fun — and most are quick, budget-friendly, and NGSS-aligned.

31 Halloween Science Experiments & STEM Activities

These Halloween science experiments are designed to work across a wide range of grade levels. Many can be adapted with simple tweaks depending on age and ability.

• Preschool & Kindergarten – Focus on sensory play, slime, oobleck, simple chemical reactions (like vinegar and baking soda), and fun observations.
• Elementary Grades (1–3) – Add prediction, recording, and NGSS-aligned guiding questions. Perfect for pumpkin eruptions, candy dissolving, and ghost balloons.
• Upper Elementary (4–5) – Explore variables, density experiments, catapults, and engineering challenges. Encourage designing, testing, and improving solutions.

👉 Teachers can easily scale these activities up or down, making them flexible for classrooms, after-school programs, or at-home learning.

Slime for Chemistry Fun

1. Pumpkin Slime – Stretch, squish, and explore states of matter.
2. Eyeball Halloween Slime – Perfect for classroom parties!
3. Witch’s Brew Fluffy Slime – A foamy slime “potion” perfect for sensory play.
4. Bubbling Slime – Add a reaction for fizzing slime fun.
5. Halloween Floam – Cool chemistry with a neat texture.

NGSS Guiding Question: How can heating, cooling, or mixing change the properties of a material?
Standards: (K–2: 2-PS1-1, 2-PS1-4)

Pumpkin Science Projects

🔎 Find more pumpkin science activities here for all of Fall!

6. Erupting Jack-O’-Lantern – Puking Pumpkin! Classic baking soda and vinegar inside a carved pumpkin.
7. Frozen Brain (Frankenstein’s Ice Head) – Explore how water changes state.
8. Rotting Pumpkin Experiment – Observe decomposition over time.
9. Pumpkin Geoboard – Use rubber bands and a pumpkin to explore shapes.

NGSS Guiding Question: What happens to plants and their parts as they grow, change, and decompose?
Standards: (K–2: K-LS1-1; 2–3: 2-LS2-1, 2-LS4-1)

Halloween Chemistry Experiments

11. Puking Pumpkin – A foamy exothermic reaction.
12. Bubbling Brew in a Cauldron – Safe foaming reaction for a witch’s potion.
13. Halloween Balloon Experiment – Inflate a balloon with a chemical reaction.
14. Fizzy Ghosts – Baking soda ghosts fizz and foam with vinegar.
15. Halloween Bath Bombs – Scented bath bombs fizz with an acid–base reaction.
16. Spooky Liquid Density Tower – Layer different liquids to explore density.
17. Gelatin Heart Experiment – Create a wiggly, creepy gelatin heart to explore states of matter.
18. Halloween Lava Lamp Experiment – Explore density and chemical reactions with a spooky twist.

NGSS Guiding Question: What happens when different substances are mixed, heated, cooled, or observed for their properties?
Standards: (K–2: 2-PS1-1, 2-PS1-2, 2-PS1-4; Grade 5: 5-PS1-3, 5-PS1-4)

Spooky Physics Experiments

19. Flying Tea Bag Ghosts – Watch a tea bag lift into the air like a ghost.
20. Ghostly Floating Drawing – Make dry-erase ghosts float on water.
21. Ghost Bubbles – Blow foamy bubbles into ghostly shapes.
22. Skeleton Bridge – Test structure and stability with simple materials.
23. Eyeball Candy Catapult – Popsicle stick catapult for Newton’s Laws in action.
24. Flying Bat Paper Airplane – Explore aerodynamics and learn about this nocturnal creature.

NGSS Guiding Question: How can forces like pushes, pulls, heat, or pressure cause objects to move or change?
Standards: (K: K-PS2-1; Grades 3–5: 3-PS2-1, 3-PS2-2, 3-5-ETS1-2)

Creepy Candy Science

24. Dissolving Candy Corn – Test which liquids dissolve candy fastest.
25. Growing Gummy Bears or Worms – Osmosis in action with spooky worms or cute bears.
26. Candy Catapult – Fling candy eyeballs to test Newton’s Laws.
27. Dancing Gummy Worms – Chemistry and physics combine to make this spooky experiment.

NGSS Guiding Question: How can matter be identified and compared based on its observable properties?
Standards: (Grades K–2: 2-PS1-1; Grades 3–5: 5-PS1-3)

Halloween STEM Challenges

29. Ghostly Structures – Build tall “ghost towers” with foam balls.
30. Halloween Secret Coding Pictures – Introduce sequencing and algorithms.
31. Halloween LEGO Challenges – STEM builds with a spooky twist.
32. Skeleton Bridge – Build and test the strength of a spooky bridge.
33. Candy Catapult – Design a catapult to fling candy.
34. Halloween Tangrams – Create spooky designs with tangrams.

NGSS Guiding Question: How can engineers solve problems by designing, testing, and improving solutions?
Standards: (Grades 3–5: 3-5-ETS1-1, 3-5-ETS1-2, 3-5-ETS1-3)

Bonus Sensory & Oobleck

33. Spidery Ice Melt – Freeze spiders in ice, then experiment with melting.
34. Halloween Oobleck – Non-Newtonian slime with a spooky theme.
35. Frozen Hands – Creepy hand-shaped ice for a melting experiment.
36. Halloween Bath Bombs – Kids create fizzy, scented bath bombs with googly eyes or creepy colors.
37. Halloween Soap Making – Melt and pour soap with Halloween molds, glitter, or spooky toy embeds for science + sensory fun.

NGSS Guiding Question: How can solids and liquids behave differently when cooled, melted, or combined?
Standards: (K–2: 2-PS1-1, 2-PS1-2, 2-PS1-4)

More Fun Halloween Learning

• Halloween Art Projects
• Pumpkin Science Activities
• Halloween LEGO Challenges
• Halloween Activities for Preschoolers

Grab the Full Halloween STEM Pack

150+ Pages of Printable Halloween-Themed Activities!
Perfect for home, classrooms, or groups. Includes:

• 25+ Science & STEM activities with instructions and printables.
• Engineering challenges (skeleton bridge, pumpkin builds).
• Brick-themed math + hands-on learning.
• Fun extras like scavenger hunts, I Spy, bingo, Would You Rather, and more.

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Halloween Science FAQ

Q: What are easy Halloween science experiments for kids?
A: Try baking soda and vinegar “puking pumpkins,” flying tea bag ghosts, or candy dissolving tests — all quick, fun, and classroom-friendly.

Q: What age group are Halloween STEM activities for?
A: These activities are designed for grades K–5 but can be adapted for preschool through middle school.

Q: How can teachers use Halloween science in class?
A: Pair each experiment with NGSS guiding questions, have students record predictions, and use simple supplies to keep prep low.