Witches Brew An Easy STEAM Activity for Halloween (Only 2 Ingredients!)

Oct 6, 2022

October’s here which means spooky seasons in full effect! Time for a fun activity that will get your #younginventor in the spirit for Halloween. Everyone knows that witches are known for making potions and concoctions in their cauldrons. So let’s make some!

Question: What will happen when we add baking soda and vinegar together?

Hypothesis: If we mix baking soda and vinegar, then… 

*Make sure to ask your #younginventor his/her hypothesis before moving onto the next step.


    • Tray (to contain the mess!)
    • Cauldrons (you can find these at the dollar store or Amazon! Or just use small cup/bowl)
    • Vinegar
    • Baking Soda
    • Food Coloring
    • Measuring spoons 
    • Measuring cups


    1. Put the cauldrons or other vessels into the tray
    2. Add 1 tablespoon of baking soda into each cauldron/cup 
    3. Add a few drops of food coloring into the baking soda
    4. Add ¼ cup of vinegar and watch the potion overflow!

PARENTS PLEASE NOTE: This may get messy! Be careful and make sure that the vessels are on an easily cleanable surface.

Let’s make some conclusions! Ask your child: 

    1. What happens when you add the food coloring? 
    2. What happens when you add vinegar? What happens if you add more vinegar? 
    3. What would happen if you added another ingredient?
    4. Is this what you expected to happen?

So why does baking soda and vinegar react when they are mixed together? Because one is a base and the other is an acid. Let’s back up – acids and bases are two kinds of chemicals. Almost all liquids are one or the other to some degree – which one it is depends on the types of ions in it. If it contains a lot of hydrogen ions it’s an acid but if it has a lot of hydroxide ions it’s a base. The baking soda is a base (meaning it has hydroxide ions), while the vinegar is more of an acid. When these two are mixed together, the hydrogen ions react with the baking soda. The result is that the carbon dioxide from the mixture rises to the top of the mixture creating the bubbles you see! As we saw in this experiment, if we mix a large amount of baking soda and vinegar in a small container with a narrow opening it erupts causing the witches brew to overflow.


Did you know we have a club designed for children ages 4-12 so they can learn the importance of inventions from an early age? As a member of the club, you and your children will learn all about inventions while completing fun, easy STEAM activities. We hope to spark the creativity of every #younginventor!

Join The Club