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How to Do The Classic Ivory Soap Science Experiment

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We are not the only family who believes that summer should be a season of STEM activities for kids. In fact, many families do STEM and science activities in the summer. Still, although we have tried hundreds of science experiments for kids, we had yet to try the classic Ivory soap science experiment.

How? I don’t know, but if you are looking for the easiest version of classic science fair projects ever, definitely try the Ivory soap science experiment. Use this soap experiment as a jumping off point for more soap science experiments and classic science fair projects.

The Classic Expanding Soap Science Fair Project

In the classic expanding soap science experiment, kids can learn how air can expand certain objects making them filled with air, but not changing their chemical structure or density in any way.

Microwave Ivory Soap Science

Ivory soap expands in the microwave due to it’s formulation.

Ivory soap is designed with a lot of air inside it, because the manufacturers wanted the soap to be able to float in the bath tub, rather than sinking to the bottom.

If you want easy science experiments, look no further than these Ivory soap science experiment. Do the expanding soap science experiment at home!

When you put the soap in the microwave, a chemical reaction happens.

When the air gets hot, the air pockets expand with moist air, forcing the bar of soap to inflate and puff up.

Turn the Ivory Soap Experiment into a Science Fair Project

All you have to do to turn this version of a science experiment into a project ready for the science fair is to ask a question, form a hypothesis, test variables, and record results.

For the ivory soap science experiment, you might try:

  • Testing other brands of soap
  • Changing how long the soap is in the microwave
  • Testing other heating methods to see if the soap still reacts the same way
  • Testing new vs old bars of soap

If you like, try microwaving other kinds of soap to see what happens.

Do all soap bars expand? Do some shrink or melt? Which soap has the biggest reaction?

What You Need to do the Ivory Soap Experiment

What You Need for a Science Fair

You’ll want to have these supplies on hand before doing your science fair project. Shop the included Amazon storefronts to make things easier and don’t forget to download the free science fair planning checklist before getting started!

Science Fair Project Planning

When you’re planning your project, you want to keep everything organized. Click the image below to get my free science fair project checklist so you can start organizing your project from the start.

You may also want to check out this list of science fair project research supplies.

Supplies for a Science Fair Project

There are so many supplies for science fair projects that are individual to each project, but if you want a general list of possible supplies and inspiration for your project, check out my selection of science fair experiment supplies on Amazon.

Supplies for a Science Fair Presentation

Your science fair presentation is important! It should look presentable and eye-catching. Check out this list of my favorite science fair presentation supplies.

science fair display board example

Ivory Soap Experiment Directions

This project is so, so simple. First, ask kids what they think will happen to the soap as a hypothesis. It’s common for them to expect it to melt or burn. If kids have done the experiment before, don’t let them give it away to the other kids!

expanding ivory soap

Heat the Ivory soap in the microwave to see what would happen.

It took about two minutes before the soap stopped expanding. I bought our soap a while ago, so I don’t know if it would have expanded even further if it was new (which could be another science experiment!).

ivory soap microwave experiment

We heated our soap several times to see if it would keep expanding, but it stopped after a minute or so, probably because all the moisture dried up.

Next, try heating other brands of soap and compare the results with the Ivory soap results.

For some reason, I thought the soap would feel soft and squishy after heating, but it didn’t. It was hot, but still hard.

soap in microwave experiment

The type of microwave and its intensity will change how much your soap bar expands. If you have a lower watt microwave, the soap will expand less.

Some microwaves will expand the soap into a huge puffy cloud, while others will cause the soap to remain somewhat small and only minorly inflated.

science fair display board example

More Classic Science Experiments

Easy Tornado in a Jar Science Experiment for Kids

Easy Slime Recipe with Borax (the original slime recipe!)

How to Do the Classic Baking Soda Volcano Science Experiment

Fizzy Dinosaur Eggs

Save this idea for later so you don't forget to use it!