This is a great way to show kids how germs are in our food and “see” the need to refrigerate our food to limit bacterial growth. This traditional kids science experiment is great for home or in the classroom. Seeing how the bacteria grows is a good foundation for a bacteria science fair project.

Learn About Germs with soda and balloon experiment - Kids Activities Blog
Let’s learn about germs! Grab a soda bottle and a balloon…

Simple Germ Experiment for Kids

Let’s see how bacteria grows in food with this easy kitchen science experiment for kids of all ages.

Related: More Science Fair Project ideas for kids

Supplies Needed for Germ Experiment

soda and balloon experiment with kids science square
We have our materials ready…let’s do science!
  • 2-3 glass soda bottles
  • Yeast
  • Balloons

Instructions for Bacteria Science Experiment

Related: Use our scientific method steps worksheets for kids

Step 1

First we drank two sodas.

This might have been the kids favorite part of the experiment.

When else do they get to drink soda at 10am?

Step 2

We dropped one teaspoon of yeast into each bottle, then we filled each halfway full of warm water and put a balloon on top:

  • One bottle went into the fridge.
  • The other went onto the counter near the oven at room temperature.

Science Discussion:  We talked about how the yeast would act as bacteria would, if the balloon blew up, then the yeast was growing.

Step 3

Step 3 - bacteria experiment - soda bottle with balloon on top in fridge - science experiment - Kids Activities Blog
Has the balloon grown?

When we got home, the balloon on the counter had blown up, but the one in the fridge hadn’t blown up at all.

We are going to watch it a few more days to see what happens.

This activity is part of our Germs Learning Unit. Thanks Jennifer for creating science lessons perfect for the kitchen.

More Fun Science Experiments & STEM Activities from Kids Activities Blog

How did your germ growth experiment turn out?

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  1. Ok-this is very eye opening! I’m glad i’ve discovered your blog, i’m going to learn lots! 🙂 Your kids are adorable!