Who wants to see a pumpkin throwing up? Most kids do! Get ready for a simple science activity the kids are going to go crazy over this Halloween. This pumpkin science activity has been dubbed the puking pumpkin around here. Although you may have seen another puking pumpkin including guacamole, this puking pumpkin experiment with baking soda and vinegar is perfect for Halloween STEM. Here, we love science activities and STEM projects!




Halloween is the perfect time to experiment with pumpkins and more specifically Jack O’ Lanterns. Pumpkins are PERFECT for so many fun ways to explore science…

ALSO CHECK OUT: Pumpkin STEM Activities

Our puking pumpkin experiment is an awesome example of a chemical reaction, and kids love these amazing reactions just as much as adults! This erupting pumpkin science experiment uses baking soda and vinegar for a classic chemical reaction. You could also try lemon juice and baking soda and compare the results!

YOU MAY ALSO LIKE: Fizzing Science Experiments

We have a whole season of fun Halloween science experiments to try. Repeating experiments in different ways really helps to solidify understanding of the concepts being presented. Holidays and seasons present numerous occasions for you to re-invent some of these classic activities.

—>>> FREE STEM Guide For Halloween


We also tried this a few years ago with a white pumpkin or ghost pumpkin which is a fun effect too! All you need is a few simple ingredients from the kitchen and you can create your own puking pumpkin for science. Forget the guacamole!

Ghost Pumpkin Experiment


Pumpkin Volcano


This puking pumpkin can get a bit messy in a fun way! Make sure to have a surface or area you can easily clean up. You can even start by placing your pumpkin in a pie dish, container, or a large mixing bowl to catch the overflow.



  • Small Baking Pumpkin
  • Baking Soda
  • Vinegar
  • Food Coloring
  • Dish Soap
  • Container (to catch the fizz)
  • Knife to carve out the hole (for adults to do!)


1. Grab a pumpkin! You can use just about any pumpkin, white or orange. Baking pumpkins are usually a great size, and you can pick them up in your local grocery store. A bigger pumpkin will work, but you will need more baking soda and vinegar, which isn’t a bad thing either!

An adult should use a knife to cut a hole in the top of the pumpkin.

Next, you will want to clean out the guts. You can even save them for a pumpkin squish bag!

2. Then you will want to carve your puking pumpkin face. Happy or scared or scary, it’s up to you but it will look funny “puking” anyway.


3. Then have the kiddos put about a 1/4 of a cup of baking soda into the pumpkin.

4. Add a squirt of dish soap if you want a foamier eruption! The chemical eruption will produce frothier bubbles with the added dish soap and create more overflow too.

5. Add a few drops of food coloring. You can also add food coloring to the vinegar for a deeper color eruption.


6. Time to add the vinegar and observe the chemistry at work!

Tip:  Put your vinegar into a container that is easy for small hands to squirt or pour into the pumpkin.


Now get ready to watch the fun as your pumpkin pukes!



Chemistry is all about states of matter including liquids, solids, and gasses. A chemical reaction occurs between two or more substances that change and form a new substance, and in this case a gas called carbon dioxide. In this case, you have an acid (liquid: vinegar) and a base solid: baking soda) when combined make a gas called carbon dioxide.

You can see the the carbon dioxide gas in the form of bubbles. You can even hear them if you listen closely.

The dish soap is added to collect the gas and form bubbles that give it a more robust pumpkin volcano lave like flow down the side! That equals more fun! You don’t have to add dish soap but it’s worth a try. Or you can even set up an experiment to see which eruption you like more.


Printable Halloween STEM Activities Pack

150+ Pages of Halloween-Themed Materials!

This Halloween project pack is suitable for home, school, and group use for kids in grades Kindergarten through elementary but is scaleable for many ages and abilities.

What’s Included:

  • 25+ Halloween theme science and STEM activities with printable sheets, instructions, and useful information all using easy-to-source materials perfect for limited-time needs. Includes a Halloween engineering pack with fun, problem-based challenges for kids to solve!
  • The skeleton activity pack includes building a skeleton challenge and a coding challenge! Try a skeleton bones bridge-building STEM challenge!
  • Halloween theme brick printable activities for hands-on learning with math that is perfect for early finishers or home fun and reinforces basic math concepts.
  • Bonus fun pack includes games and activities to round out your Halloween theme activities such as I Spy, bingo, matching, Would You Rather cards, scavenger hunt, word search, A-Z Halloween hunt, and a coloring page.
  • Halloween STEAM Pack includes artist-inspired projects by Warhol, Lichtenstein, and more!