Let’s Learn About Digestion! An easy science experiment & sensory activity

I’m coming at you today with a simple science experiment that your kids are going to love! You, eh, maybe not so much. This activity will teach your kids the basics of how their stomach works and is great for preschool and elementary science students, though to be fair my middle schooler giggled just as much at the results.

Not only is this experiment a great science experiment but it’s a great sensory activity too! It’s especially great because your child can experience the sensation of digestion without getting their hands dirty. Ah, life with the kid who has sensory processing disorder ;)


digestion science experiment

What you need:

a balloon

vegetable oil

white vinegar

a piece of bread or handful of oatmeal



-Pour a few drops of the oil into the balloon and rub the balloon between your hands so the oil lines the inside of the balloon. Tip the balloon upside down so any extra oil will drip out.

-Break some pieces of bread off and drop into the balloon, OR, drop about 15 oats into the balloon.

-Pour about 1 tsp of the white vinegar into the balloon, you may need a bit more if you add more food.

-Squish the balloon around for a minute or so. Then carefully start at the fattest part of the balloon and squeeze up. Ask your kids to describe what comes out.



In this experiment pretend the balloon is your human stomach. Your stomach contains acid that helps break down the food you eat so your body can get the nutrients it needs from the food. Because we don’t want to work with actual stomach acid (gross!) we are going to use white vinegar, which is still an acid but not nearly as strong (or gross!) as stomach acid. Because stomach acid is so strong your stomach has a lining to protect it, we replicated this by pouring the oil into the balloon. Your stomach lining isn’t really made from vegetable oil, it’s made from mucous (double gross!) but the oil lines the inside of the balloon the same way the mucous lines your stomach.

Because the balloon isn’t part of a real human we’ll drop the food into the stomach and pretend it got there by being swallowed. When the food gets to the stomach the acid starts doing it’s thing! Your stomach is a big muscle so when the food reaches it, it will contract and release so it can swish the acid around, and you’re doing the same thing by squishing the balloon around your fingers.

What happens when you squish the contents out of the balloon? The food is dissolved! This is exactly what your stomach does before passing the food along to your small intestine. The small intestine is the organ that digests and absorbs the nutrients in the food, but it can’t do that with a big chunk of food. Your stomach’s job is to break the food up into tiny pieces so when it moves to the small intestine those nutrients are ready to be absorbed and used by your body!

Pretty awesome, isn’t it?


I used a potato or whole wheat bread?

I used a piece of fruit?

I used a chunk of cheese?

I used milk?

I used only water?

Try it out for yourself and see! Happy experimenting!

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