What? Exploding soap you say?!?


Last week we did the coolest experiment ... EXPLODING SOAP!

First of all, I passed around a bar of Ivory soap and we smelled it, touched it, and thought of as many words as we could to describe it.

Then I told the class we were going to put the bar in the microwave and heat it up.

But first the kids came up with their own predictions as to what on earth was going to happen. Nobody actually thought it would shrink. Smart kids!

Here it goes ...

Whoa! Can you believe this? The kids were so excited that I'm sure we could be heard from the other end of the school.

We tried it again, but this time put food colouring on the soap. I was hoping for a rainbow effect.

Well, not exactly a rainbow, but still pretty cool!

Scientific explanation? The soap is full of moisture and small air bubbles. When the bar heats up, steam is produced and the air bubbles expand. Voila! Exploding soap!  As the steam escapes (you can't see any steam ... but that's what I read :)) the bar cools down and the air bubbles contract so the whole mess of soap starts to shrink a bit.

How does this relate to the curriculum? Heat can change matter.

Here's the experiment sheet we used. It's very simple ... just drawing pics to represent the beginning, middle and end of the experiment.

Have fun!


  1. Thank you for sharing this! Felix and I studied it this morning (we have Veteran's Day off). We don't have a microwave at our house :( BUT we are thinking about doing it at someone else's house!

    First in Maine

  2. I love doing that experiment! The bad part is that the microwave smells like ivory soap for a loooonnnggg time after that anytime it is used.

  3. That is soo cool! I think I will have to try this one out with my kids!

  4. This is a favorite of mine!! :) Love it!

    Happy Remembrance Day!

    The Hands-On Teacher in First!

  5. I love this experiment! Thanks for sharing it!
    I Dream of First Grade

  6. How cool is this? Thanks for sharing!

    First Grade and Fabulous

  7. This is really neat Barbara! I've never done this before. Thanks for sharing. :)

    Granny Goes to School

  8. What wonderful and exciting fun! I never knew this would happen with soap (never thought of soap in the microwave either!).
    Conversations in Literacy

  9. This looks like SO much fun! You kids must love science!

    Chickadee Jubilee

  10. What a blast!! I can't wait to try this!

  11. Thank you so much for sharing this one. We just finished up our matter unit and how matter can be changed. I will be putting this experiment to use!
    Think all night…..Teach all day

  12. Great idea! Messy and fun!

    I'm having a GiveAway.
    Please stop by.


  13. That is pretty cool stuff. Now, I need to find time to fit these little experiments into my day!
    ❀ Tammy
    Forever in First