I had the idea to make this bubbling slime recipe into a witches brew with googly eyes to add a bit of creep factor to this fun science project for kids.
Although it was meant to just be a classic science project, it ended up as a STEM activity because our first version of these Halloween slime recipes didn’t work and we had to figure out why!
Although some people might see an activity that goes wrong as a failure, activities that don’t quite work are actually a great way to teach critical thinking and problem solving to kids.
Monkey was able to see that will a little ingenuity she was able to solve the problem using her brain and the technology available to her.
If you’re looking for a super-simple Halloween activity to do with your kids, try this slime fun activity and make bubbling eye of toad witches brew!
How The Bubbling Slime Experiment Works
Baking soda is a base (NaHCO3) and vinegar is an acid (HCH3COO). When bases and acids mix, they try to neutralize each other. The byproduct of this reaction is the gas carbon dioxide. The slime make the reaction seem cooler because you can see the gas bubbles rise to the surface.
Consequently, this has been one of our favorite Halloween science experiments!
How to Make Bubbling Slime
If you can’t tell yet, we love slime at our house. Slime fun is definitely one of our favorite types of fun!
What you’ll need for this bubbling slime activity:
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Day 1 (or the morning before)
Make your slime by mixing about 3 teaspoons of Xantham gum in 3 cups of vinegar. Add the food coloring. Stir until most of the large clumps are out. The mixture will thicken right away, but it will still look lumpy.
Place the mixture in the refrigerator overnight, or for a few hours.
Mix the slime mixture with a whisk until the lumps are gone. It shouldn’t take more than a minute or two of stirring.
Spread about a 1/4 inch layer of baking soda into your shallow pan.
Pour the slime over the baking soda and sprinkle the googly eyes on top.
Watch the witches brew start to bubble up and “boil” the eyes as the baking soda reacts with the vinegar and releases carbon dioxide into the air.
Where Our Bubbling Slime Experiment Went Wrong
At first, we had our bubbling slime inside a mason jar. We had a layer of baking soda and a layer of slime on the top. However, the slime was so thick that the bubbles remained trapped under the weight of the slime and it wasn’t reacting as much as we wanted it to.
When we moved the whole project into a shallow container, it worked much better.
However, after our bubbling witches brew potion experiment, Monkey put the slime back in the mason jar with the baking soda and stirred it up.
It started to foam and rise out of the container like a baking soda volcano. The slime looked like it was breathing, which Monkey thought was appropriately creepy for Halloween.
We discussed how we also release carbon dioxide when we breathe. There is more than one way to try every experiment! That’s what makes STEM activities so cool.