Funny Foam

Another rainy day experiment for the Joe and I, with Jacob watching from the bouncer. I found a recipe for elephant toothpaste on Pinterest, but after doing the experiment I think a more suitable name for it would be “Funny Foam” because Joe cracked up laughing when the foam came out the top of the bottle.

Here is the supply list:

  • 16 ounce plastic bottle (clean)
  • 1/2 cup hydrogen peroxide liquid (3%)
  • 1 Tablespoon (one packet) of dry yeast
  • 3 Tablespoons of warm water
  • Dish soap
  • Small cup for mixing yeast and water
  • Safety goggles


Be prepared for a soapy mess! The bottle will overflow so you will need to work on a surface that is easy to clean up.


  1. Put safety goggles on and mom, dad or another adult should pour the peroxide in the bottle. I used a funnel to get it all in.
  2. Add dish soap to the peroxide and swish around to mix.
  3. In the small cup, combine the warm water and the yeast and mix until pretty much combined. It’s ok if there are a few chunks.
  4. And now for the fun part! Pour the yeast water mixture into the bottle, again using a funnel and watch the funny foam overflow!

image image

Joe had lots of fun touching it, playing in it, scooping and pouring it back in the bottle. I felt fine about letting him play in it after the experiment was done. I just poured the peroxide in the bottle initially because I didn’t want him to drink it, and after the experiment it is just dish soap, oxygen and water.


Although I learned a lot about the science of this experiment, I didn’t go through it with Joe in too much detail yet. I did tell Joe that the bubbles were full of oxygen. But by the time I got to explaining how the yeast acted as a helper (catalyst) to remove the oxygen from the hydrogen peroxide creating lots and lots of bubbles or foam, Joe had moved on to something else. He has the attention span of…well, a two-year old. 🙂

I think we will do this one again and again and I will go into a little bit more of the science behind the fun each time. Maybe next time I will explain that the bottle gets warm because with the experiment we created an exothermic reaction, making not just lots of foam, but heat too.

And when he gets a little older and more curious about science we might make it a true experiment where we try and answer the questions below.

  1. Does the amount of yeast change the amount of foam produced?
  2. What happens when you add more or less water? More or less yeast?
  3. Does the experiment work as well if you add the dry yeast without mixing it with water?
  4. Does the size of the bottle affect the amount of foam produced?
  5. What happens when you add food coloring?

Clean up is simple, wipe with a sponge or cloth and pour any extra liquid down the drain. It’s just water, soap and oxygen now.

There are so many experiments, lessons and information at our fingertips now. The internet is a wonderful (and terrible) thing. I either don’t know or have forgotten some of the science, history, English and math lessons I learned in school, but with the internet I can teach Joe and learn at the same time. I think my authentic enthusiasm for these lessons helps make learning fun for all of us.


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