With toddler grandchildren around, I’m always looking for safe slime recipes. This yogurt slime activity is a go-to favorite in our house—especially when you want younger kids want to join the fun without the worry of what’s in the ingredient list.

Made with just plain yogurt and cornstarch, this recipe is non-toxic and technically taste-safe (though we don’t recommend it as a snack 😄). It’s a great introduction to sensory play and early kitchen science!

We love switching things up with seasonal twists—like our pumpkin slime (definitely not edible) in the fall or candy cane slime around the holidays—but this yogurt version is perfect any time of year. You can keep it simple or mix with a favorite natural food coloring.

Yogurt slime has two main ingredients. Optionally, you can add your food coloring of choice. This is easy to make when you are looking for something spontaneous to do with your young ones.

Scroll down for the full recipe and step-by-step photos!

Supplies for the yogurt slime:

Supplies:
1 cup corn starch
1/2 cup plain yogurt
Purple (or other color) food coloring (optional)
Small bowl
Spoon

Directions:

Measure the yogurt and corn starch. Then, gather the other supplies.

2. Mix the yogurt and corn starch in a bow. Stir well. You may need to knead the slime with your hands.

3. Once the ingredients are incorporated, add 2-3 drops of food coloring, and continue to knead until the dough has a slime consistency.

4. If the slime is too wet, add 1 teaspoon of cornstarch at a time. If it is too dry, add one teaspoon of yogurt at a time.

The Science Behind Yogurt Slime – For Older Students

For your older kids or students, here is a more detailed explanation of the chemistry behind the yogurt slime. You can use a glass of whole milk, water, and some oil as visuals. Have your child pour a glass of water, then drop in some oil. (You don’t need to much.) They can then see the fat droplets that do not mix. However, we cannot see the fats that are suspended in the water that makes up milk.

Did you know that two ingredients in milk are milk fats and water (among other substances)?

You can’t see the fat droplets in whole milk; the fat and water do not separate. Milk is a good example of a colloid.

When we pour a glass of milk and look at it, we don’t see a fat layer and a water layer. The fat particles remain spread out in the water.

Even though fat and water don’t normally mix, just like the oil in water pictured here. But, in milk, the fat stays suspended instead of floating to the top or sinking to the bottom. That’s what gives milk its smooth, creamy texture—and it’s the same kind of science at work in yogurt!

A colloid is a special type of mixture where tiny particles stay evenly spread out within another substance—without dissolving or settling. Milk is a colloid made of fat droplets dispersed in water.

Yogurt is also a colloid, made of tiny proteins and fats evenly spread throughout, giving it a thick, spoonable feel that’s perfect for making slime.

When you mixed the yogurt with cornstarch—a common thickening agent—something interesting happened, didn’t it?

Cornstarch is made almost entirely of starch, which is a type of carbohydrate found in plants—especially corn kernels. Starch is made up of long chains of molecules called amylose and amylopectin.

When you mix yogurt with cornstarch—a common thickening agent—something interesting happens.

A thickening agent is a substance that makes liquids denser or thicker without altering their flavor or chemical composition. In cooking, cornstarch is often used to thicken sauces or soups, and in science play, it helps turn runny mixtures into gooey, moldable materials.

In this case, the starch molecules in cornstarch begin to absorb water from the yogurt. The cornstarch traps the liquid. A thicker and more stretchy substance is created. In this activity that was the slime!

Here’s how it works:

When cornstarch is mixed with a liquid and heated (or stirred really well), the starch molecules absorb water and swell up.
These swollen starch granules trap the liquid, making the mixture thicker.
The more you stir and mix, the more the molecules tangle together, turning a thin liquid into a smooth, gooey texture—like slime!

We say that this is a type of non-Newtonian fluid—which means it doesn’t behave like a regular liquid. If you squeeze or press it quickly, it acts more like a solid. But if you let it ooze and move slowly, it flows like a liquid.

I hold a master’s degree in child development and early education and am working on a post-baccalaureate in biology. I spent 15 years working for a biotechnology company developing IT systems in DNA testing laboratories across the US. I taught K4 in a private school, homeschooled my children, and have taught on the mission field in southern Asia. For 4 years, I served on our state’s FIRST Lego League tournament Board and served as the Judging Director. I own thehomeschoolscientist and also write a regular science column for Homeschooling Today Magazine. You’ll also find my writings on the CTCMath blog. Through this site, I have authored over 50 math and science resources.