Try this magical milk experiment and impress your kids with the power of science. Includes tips for scientific investigation for kids.

I totally remember doing a milk experiment like this when I was in grade school, but the version I got to do was way less cool.

We sprinkled pepper on a pan of milk and then watched it zoom away when we touched the milk with the cotton swab.

I thought it was pretty cool at the time.

After seeing the results of this magic milk experiment, I concluded that this one was way better.

Supplies Needed

To do this magic milk experiment, you’ll need a few things from around the house.

dish soap
food coloring
full fat milk
cotton swab
shallow dish

Got your supplies?

Let’s make the magic happen.

How to Set Up the Experiment

The set up is really easy, which is great because your kids will want to do this one over and over again.

Step One: Pour Milk

You’ll need just a thin layer of milk. Enough to cover the bottom of your dish so it looks nice and opaque.

Make sure the milk you are using is full fat.

We used whole milk.

Step Two: Dot with Food Coloring

We dotted the milk all over with food coloring for the best effect.

Definitely use liquid food coloring or even liquid watercolors for this step.

I noticed that the colors stayed pretty true, so if you want colors that are not straight out of the bottle, you may have to try mixing them before adding them to the milk.

Step Three: Dip Cotton Swab in Dish soap

Pour dish soap into a small container, then dip a cotton swab in it.

Touch the milk with the cotton swab and hold it still.

Watch the milk “run away” from the soap.

I love watching the tie-dye magic happen every time!

What’s really fun about this experiment is that the color swirls are different each time you do it!

My youngest (age 22 months) enjoyed swirling the colors around herself with the cotton swab.

I’ll admit that looked pretty cool too.

Why This Happens

The key to this experiment is the full fat milk.

Once the soap touches the milk, the little soap molecules chase the fat around to break it up.

This is why soap is so great at washing the grease from pots and pans.

Because this happens on a molecular level, we normally wouldn’t be able to see it.

But because we added food coloring, it gets swirled around by the soap molecules and we can see the effect.

This is also visible when you sprinkle pepper on milk like I did when I was a kid. It’s just not as colorful and exciting! 🙂

For Further Research

If you want to turn this into a full-fledged scientific investigation, consider trying the experiment with different milks (oatmilk, almond milk, goat milk, heavy cream, skim milk, etc.).

Keep the process the same, just exchange the whole milk for other liquids.

Record your findings with your kid in a chart. Include photos if you can.

Make a whole science journal about it.

Let us know in the comments what you find out!

Your Turn to Try This Magic Milk Experiment and Impress Your Kids

It’s time to try this simple STEM experiment with your kids.

Even if they don’t really “get it” (I’ll admit, I’m not sure I fully comprehend the science behind it either!) it’s still a fun and easy experiment to try!