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Exploding Ivory Soap – An Easy Kids Science Experiment

This is the easiest science project EVER! I've seen it before, but no one explains it as well as this one. Great explanation and instructions!

You know how something can be super fun and exciting until someone tells you that you have to do it? And then it loses all its luster and seems like something that is boring and hateful?

That’s what happened to Super Science Summer.

My kids love science, and they begged me to let them do experiments all the time.

And then I decided to do a super cool 11-week series of summer science on my blog, and they balked. By week three, they were all like, “Do we have to do science again?” and “I would rather just watch tv, Mom.


So Joe and I did a few experiments on our own and then quickly petered out, and that’s why there hasn’t been anything new for a while now. No involvement on the part of the people who were meant to enjoy all this sciencey summer fun made for a big zero.

Go with the flow, right? What else can I do?

I did, however, turn the tv right off. They haven’t quit complaining about that, and it’s been a couple of weeks.

So anyway, I have snuck in a couple of fun science activities in the weeks since they began boycotting all things interesting. They each went to science camp for a whole week (two different weeks, for their respective age groups), and they have done some vinegar and baking soda explosions out on the back porch in the evenings. Other than that, though, it’s been a summer of doll houses and American Girl dolls and lots and lots of Usborne books.

Back to this particular science experiment. This is an oldie but goodie that I have seen over and over again in different books and on different websites.


  • Microwave
  • Ivory soap – Must be Ivory name brand, no other will work. Also, you will want at least a 6-pack because once or twice simply isn’t enough.
  • Microwave-safe plate


  1. Unwrap soap.
  2. Place soap in the center of plate.
  3. Microwave on high for 1.5-2 minutes, watching as closely as possible.microwave-ivory-soap-watching
  4. Let the soap cool for a minute or so. Be careful for any hot spots. If there is any un-exploded soap chunks, they will be super hot. We removed those and tossed them back in the microwave to re-explode them.
  5. Remove soap from microwave and marvel at its shapes.


The Science

Microwaves make water molecules get excited, vibrate, and move really fast. Molecules that are moving really fast bump into each other a lot and move really far apart.

When the water molecules start moving fast and getting further apart, they stretch out the spaces in the soap and make it expand in all sorts of fun and interesting ways, as you see below.


Extend the Experiment

I asked my girls how we could change the experiment, and Allie’s suggestion was to cut the soap into little pieces. I expected this to totally ruin the experiment, but the results were pretty cool.

I’m not going to tell you what happened. You’ll have to do it and find out for yourself.


One last thing. I cannot get the smell of Ivory soap out of my microwave. It’s not a bad smell, but it is odd to smell mingled with the scent of yummy food cooking. Just thought you’d want to know ahead of time.



© 2016 – 2018, Tara Ziegmont. All rights reserved.

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