Array Bubbling Fizzy Cauldron STEM | Montessori From The Heart

Bubbling Fizzy Cauldron STEM

Bubbling Fizzy Acid-Base reaction STEM Kids Activity Color Mixing Free PDF

Bubbling fizzy color-mixing cauldron acid-base science experiment to promote STEM education in toddlers, preschoolers, and kindergartners. Video Tutorial is Included.

Whether we are looking for a Leprechaun’s pot of gold at the end of the rainbow or brewing a colorful potion, make this Bubbling Fizzy Cauldron STEM experiment with a few simple household ingredients! Besides, by skipping dish soap, this science experiment is safe for babies and toddlers who are still mouthing objects! Most importantly, this kid-safe taste-safe color-mixing activity is perfect for all ages and will expose little scientists to the most satisfying-to-watch acid-base reaction.

Bubbling Fizzy Cauldron STEM TASTE-SAFE Kids Activity


Here is a list of supplies you’ll need for Bubbling Fizzy Cauldron STEM:

  1. a waterproof tray to catch the spillover
  2. a sensory filler (we are using recyclable shredded grass)
  3. vinegar
  4. baking soda and a scoop (love this olive-wood scooper)
  5. food coloring
  6. cauldrons, bowls, or cups

*Bubbling Fizzy Cauldron STEM TASTE-SAFE Kids Experiment
*Bubbling Fizzy Cauldron STEM TASTE-SAFE Kids Experiment


Below are the instructions on how to conduct this taste-safe Color-Mixing Science Experiment:

First, set up your waterproof tray to catch the spillover. (Grass filler is optional.)

Secondly, arrange cauldrons and add a heaping amount of baking soda to each.

Next, add the desired food coloring to each cauldron’s baking soda. Next, MIX baking soda and food coloring. (You want the food coloring to ‘coat’ and mix with baking soda so that the eruption is colorful.

If you do not mix it, the vinegar might activate with baking soda that has not been ‘colored’, and you will have a colorless eruption.)

Lastly, pour vinegar over the baking soda cauldron, and watch the bubbling fizz erupt!


Video Tutorial

Instead of vinegar, you can use lemon/ lime juice/concentrate or freshly squeezed citrus.


This bubbling fizzy cauldron STEM experiment is TASTE-SAFE for little ones who are still mouthing things since they are using basking soda and food coloring! However, taste-safe does NOT mean edible!

Please note you can add a squirt of dish soap. However, your experiment will NO LONGER be TASTE-SAFE!

We still want to deter little ones from eating anything that is not food! Good habits will ensure SAFE play! So, if they put it into their mouth, calmly say, “No, not for eating. Not in your mouth.” or “Do not put it in your mouth. This is not food.” Or stick a tongue out and make a yucky /disgusted face. Most importantly, model appropriate ways to play. If the behavior persists, remove it and introduce it later.

RED Bubbling Fizzy Cauldron STEM
RED Bubbling Fizzy Cauldron STEM

The best part of this experiment is that you can conduct it multiple times! Since when you pour vinegar over the baking soda, the vinegar will only activate the top layer of it, leaving the bottom layer intact.

So, try after your first eruption, add more vinegar, and watch it fizz again! If you pour the vinegar and nothing happens, add more baking sade!

Bubbling Fizzy Cauldron STEM TASTE-SAFE Kids Sensory Bin
Bubbling Fizzy Cauldron STEM TASTE-SAFE Kids Sensory Bin


This STEM is also a fun color mixig experiment!

Mix blue + yellow to make green.

Mix blue+ red + (optional pink) to make purple.

Primary and Secondary Color Mixing PDF Freebie


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PURPLE Bubbling Fizzy Cauldron STEM
PURPLE Bubbling Fizzy Cauldron STEM

Bubbling Fizzy Cauldron STEM VARIATIONS:

  • Set 7 cauldrons and add rainbow colors to each
  • For Halloween, add spooky eyeballs or other accessories into the cauldron
  • Harry Potter or witches fans? Make it a brewing potion!


What’s the science behind Bubbling Fizzy Cauldron STEM?

It’s chemistry! It’s an acid-base reaction! This taste-safe Color-Mixing Science Experiment is simple. It’s fun! And it never ceases to amaze little people!

When baking soda (a base) and vinegar (an acid) are mixed together, they react with each other because of an atom exchange. (Baking soda receives a proton from vinegar). And one of the products this reaction creates is carbonic acid which is very unstable. Thus, carbonic acid instantly breaks apart into water and carbon dioxide molecule. And since the carbon dioxide molecule is now free of its other chemical bonds, it can escape, bubbling forth as a gas. As a result, this chemical reaction releases gas that bubbles and fizzes, making it a fun sensory acid-base kids’ experiment. The food coloring helps you see the bubbles a little better.

So, in a nutshell, it is the CO2 gas that is responsible for all the fizzing as the gas escapes the solution!

A few discussion questions you can ask your kids to think about with Bubbling Fizzy Cauldron STEM:
  • What would happen if you added coloring to vinegar instead of baking soda? (Hint: Same result, but you can skip mixing baking soda with coloring.)
  • What if we changed how we added the ingredients together? For example, if we poured the baking soda into the vinegar instead of the other way around? (Hint: Same result, since it the MIXING of ingredients that matters and not the order).
  • Can this potion be used for anything? (Hint: Baking soda and vinegar make a great household cleaner!)

Bubbling Fizzy Cauldron STEM St Patricks Kids Science Experiment
Have you tried Potion Color-Mixing Science Experiments?
Leave a comment on whether you liked this Bubbling Fizzy Cauldron STEM!

For more Acid-Base Reaction STEM …

See here Balloon Baking Soda Vinegar Kids Science.


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