Children place the little ghost on the ground. Then, everyone takes a few careful steps backward.
Nothing happens. Someone giggles. Another child whispers, "Is it going to pop?"
Every pair of eyes stays locked on the bag as it slowly begins to puff up. The ghost grows bigger... and bigger... until suddenly...
POP!
Foamy orange bubbles burst across the ground, and children erupt into laughter before immediately asking if they can make another one.
That's what makes these Bubbling Boo and Pumpkin Bombs so unforgettable. Children aren't simply watching a science experiment. They're building anticipation, making predictions, and celebrating every wonderfully surprising explosion together.
If your family loves fizzing, bubbling, and surprising science, be sure to explore our Science Experiments for Kids collection filled with hands-on activities that invite children to predict, experiment, and discover through play.
If these Bubbling Boos leave your little scientists asking for "just one more," don't miss our Baking Soda and Vinegar Experiments for Kids collection packed with colorful eruptions, bubbling reactions, and unforgettable science adventures.
Supplies
One of the most exciting things about Bubbling Boos is that they begin with a few ordinary household ingredients before transforming into a Halloween surprise children can't wait to experience. Every ghost and pumpkin starts small... but it certainly doesn't stay that way.
You'll need:
- Baking soda
- Cornstarch
- White vinegar
- Food coloring (orange for pumpkins)
- Sandwich-size zip-top bags
- Permanent marker
- Toilet paper
- A measuring spoon
- An outdoor space for launching your Bubbling Boos and Pumpkin Bombs
.jpg)
How to Make Bubbling Boos & Pumpkin Bombs
Step 1. Draw your Halloween characters
Use a permanent marker to draw friendly ghost faces or smiling jack-o'-lanterns on sandwich-size zip-top bags.
Children often spend just as much time deciding on funny expressions as they do waiting for the explosions.
Step 2. Build the bubbling mixture
Pour vinegar into each bag until it's about one-third full. Add a few teaspoons of cornstarch, then stir in orange food coloring if you're making Pumpkin Bombs. Seal the bags tightly and gently mix until everything is combined.
Now the ghosts are almost ready...
All that's missing is the surprise hidden inside.
Step 3. Make the baking soda bombs
Place a spoonful of baking soda in the center of a small square of toilet paper. Fold the paper around the baking soda until you've created a little packet.
Each tiny packet holds the surprise that brings your ghost or pumpkin to life.
Step 4. Stand back and wait
Open each bag just enough to drop in one baking soda packet, then seal it immediately. Give the bag one quick shake and gently set it on the ground.
Now comes everyone's favorite part. The bag slowly begins to puff up.
Children watch. Giggle.
Take another step backward.
POP!
Colorful fizzing bubbles burst free, and almost every child immediately asks to do it again.
Why Kids Love Bubbling Boos
Children don't rush away after setting the bags on the ground.
They wait.
Every few seconds someone leans in just a little closer to see if anything is happening. Then, the bags begin to swell.
Little by little. The ghosts puff up. The pumpkins grow rounder. Giggles grow louder. Everyone takes another step back...
...just in case.
Then comes the moment they've all been waiting for.
POP!
Colorful bubbles burst across the ground, and before the excitement has even settled, children are already asking if they can make another one.
That's what makes Bubbling Boos so memorable. Children aren't simply watching a baking soda reaction. They're building anticipation, making predictions, and celebrating every wonderfully unexpected explosion together.
Extend the Play
- One explosion almost always leads to another.
- Invite children to decorate each ghost or pumpkin with its own funny face before predicting which one might pop first. Will the smiling ghost win? Will the pumpkin surprise everyone?
- Try making several Try making several ghosts or pumpkins with different amounts of vinegar or baking soda and see whether children notice any differences in how quickly they begin to puff up.
The waiting becomes part of the game. Sometimes everyone counts together.
Sometimes the whole group falls completely silent. Then...
POP!
Every round feels just as exciting because no one ever knows the exact moment the surprise will happen.
Frequently Asked Questions
Do Bubbling Boos have to be made outside?
Yes. These fizzing ghost and pumpkin bombs are designed to burst open, so an outdoor space makes cleanup quick and easy while giving children plenty of room to stand back and watch.
Why is the baking soda wrapped in toilet paper?
The toilet paper creates a small packet that delays the reaction just long enough for you to seal the bag and set it down before the fizzing begins.
Can we make only ghosts or only pumpkins?
Absolutely! You can make an entire batch of friendly ghosts, a patch of smiling pumpkins, or mix both together for even more Halloween fun.
What age is this activity best for?
Preschoolers, elementary-aged children, and even older kids love the suspense of watching Bubbling Boos puff up before they pop. Because the bags build pressure, an adult should always supervise this activity and help younger children with setup.
Why do we add cornstarch?
The cornstarch creates thicker, bubbly foam that makes each explosion even more colorful and exciting.
More Halloween Science Activities to Explore
If your little scientists couldn't wait to launch another Bubbling Boo, here are a few more Halloween experiments filled with fizz, surprises, and unforgettable reactions.
Watch ordinary eggs transform into glowing ghostly surprises through an unforgettable Halloween science experiment.
Plant a tiny pumpkin seed and surprise children as a jack-o'-lantern magically appears before their eyes.
Create icy-cold ghost artwork that dries into soft, raised paintings children can't stop touching.
Discover our complete collection of Halloween crafts, science experiments, sensory play, and festive family activities designed to make the season unforgettable.
Waiting for the Pop
Some science experiments surprise children the moment the ingredients are mixed. Bubbling Boos asks them to wait.
They watch. Wonder. Giggle.
Take one more step backward. Then, without warning...
POP!
We hope these Bubbling Boos inspire your family to laugh together, make predictions, and discover that sometimes the most exciting part of science isn't the reaction itself.
It's the wonderful anticipation that comes just before it.
Save This Idea for Later
With just a few simple household ingredients, Bubbling Boos transform an ordinary baking soda experiment into a Halloween science adventure filled with suspense, laughter, and unforgettable pops.
Save this Bubbling Boos & Pumpkin Bombs activity to Pinterest so it's ready the next time you're looking for a Halloween science experiment, a fizzing outdoor activity, or a playful way to surprise little scientists with hands-on discovery.
Play Recipes for Kids
Looking for even more hands-on fun? Explore our Play Recipes for Kids collection, where you'll find colorful slime recipes, sensory play ideas, homemade paints, play doughs, science experiments, and dozens of creative activities designed to inspire curiosity, imagination, and joyful childhood memories.
