Exploding bags Halloween science is delightful STEM activity that fizzes, foams, and POPS with kid-safe excitement. Set it up in minutes with pantry items, add silly faces, and get ready for a real blast Halloween science fun.
Exploding bags Halloween science overview
One of my friends’ kids requested a “science explosion day” and this was one of the first activities that came to mind.
It’s got science and explosion, but not anything too big or too explosive.
This simple experiment turns ordinary Ziplock bags into mini pop-labs that kids will love.
It’s perfect for home, school, and would be so much fun as a last-minute Halloween party surprise.
What kids notice and learn
Kids personalize the experiment by sketching silly Halloween faces on the bags, then watch the delayed reaction unfold.
The paper-towel “time release” invites cause-and-effect talk, builds vocabulary (acid, base, gas, pressure), and keeps the setup manageable for preschool science.
One of the best things about this experiment is its simplicity so that it can be done a few times in a row. Each time you repeat, you can change various parts and compare the results (more on this below!).
🎃 Baking soda and vinegar are the ultimate dynamic duo and there are so many ways to use them for Halloween, including:
- Halloween balloons (I did this one as a kid myself – thanks, Mom!)
- Fizzing Halloween spiders
- Creepy Frozen Halloween Hands
- Pumpkin Fizz with Mini Plastic Pumpkins
Materials
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- Vinegar
- Baking soda
- Sandwich-size zipper bags
- Paper towels – half-sheet size works great
- Permanent marker
- Optional – food coloring or liquid watercolors
- Tray with sides – a baking sheet also works perfectly
How to make exploding bags Halloween science
- If you’d like, use a permanent marker to draw a Halloween face on the empty zipper bag.
- Place 1 to 2 tablespoons of baking soda in the center of a paper towel, fold it a little so the powder is tucked inside.
- Pour vinegar into the bag – about ½ cup for sandwich bag size. Add a few drops of coloring if you’d like for ✨drama. ✨
- Carefully pop the paper-towel into the bag, quickly seal it, and set the bag on the tray.
- Step back and watch! The paper towel slows the mix just long enough for kids to set it down and observe the gas inflate the bag until it “explodes” with a soft pop.
The science behind exploding bags Halloween science
When an acid (vinegar) meets a base (baking soda), a chemical reaction creates carbon dioxide gas.
The gas has to go somewhere, and inside a sealed bag it fills every corner, building pressure like a mini balloon.
The paper towel acts like a delayed-release packet, buying time before the fizz begins.
This is perfect preschool science vocabulary practice: reactants, reaction, gas, pressure, and observe.
Extension ideas beyond exploding bags Halloween science
There are a bunch of extensions to add to this experiment for kids to explore a variety of science concepts. We LOVE an experiment that can be repeated over and over to explore different variables.
- Try different amounts of baking soda and vinegar. What happens if you double each ingredient?
- Try warm vs. cold vinegar and chart the time to inflation.
- Change bag size and discuss how volume affects pressure. What happens if you repeat this experiment in quart- and gallon-sized bags?
- I loved using this in the classroom at Halloween parties as a way to get everyone pumped and full of Halloween excitement.
Frequently Asked Questions
Start with about ½ cup vinegar and 1 tablespoon baking soda. Adjust up or down to explore different inflation speeds.
It delays the reaction so kids can seal and safely set the bag down, then observe the “ballooning” start.
You’ll naturally hit observation, prediction, measurement, and data recording – core early STEM and great for preschool science documentation.
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