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Learning Laboratory: Microwaved Soap

microwaved soap bar

I microwaved marshmallows all the time as a kid. I loved the way the marshmallow would double or triple in size as the heat caused the molecules inside to move more and more quickly. When I heard that bars of soap were an equally effective way of demonstrating Charles’s law, I knew we had to give it a try, and it worked beautifully!

All of the soap on this plate comes from one sample-size bar of soap! Marshmallows collapse once they are out of the microwave, but the structure of soap allows it to hold its shape. It was easy to slice because the air bubbles make it so soft, and the sliced pieces show the new air bubbles very clearly. The kids were really tempted to eat it – I guess it looks like candy to them. Maybe we’ll give marshmallows a try for a real treat sometime!

This only works if you use soap that floats – sinking soap will bubble up. Also, the scent from the soap will fill your entire house – so pick soap with a light or no scent!

learning laboratory at mama smiles

MaryAnne is a craft loving educator, musician, photographer, and writer who lives in Silicon Valley with her husband Mike and their four children.

17 thoughts on “Learning Laboratory: Microwaved Soap”

  1. Levitra kaufen

    I searched Google for cherubs and I found your blog :-) I like your blog, well done!

  2. The night before moving, we tried this with a bar of Dove soap. The scent was so overpowering we spent the rest of the evening with all our windows open! It didn’t puff up like marshmallows do, just bubbled all over the plate. We’ll try again sometime in a well-ventilated area and with a smaller bar of soap.

  3. I am definitely going to try this!!!!! HOw cool!!!!!!!!! We have a microwave s’mores maker and I immediately thought of pulling it out when you mentioned microwaving marshmallows.

  4. Adding this to my list of things to try with my cherubs. It’s interesting to read Natalie’s comment about Dove soap being particularly good for this.

  5. I heard that Dove soap is especially good for this experiment, but I wasn’t brave enough to try it yet. Microwaved marshmallows sound like fun too!

    1. @Natalie – The soap stops expanding at a certain point, so you don’t have to worry about it exploding, which is nice. We didn’t use Dove soap, but I have heard the same thing about it being best.

  6. Elisa | blissfulE

    How fascinating! Maybe hotels should start doing this so it looks like they give you more soap. :)

  7. Mmmmmmmm marshmallows…… I love this idea, and keep meaning to do it. It’s on my long list of meaning to do items.

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