Science Experiments for Kids: Exploring Surface Tension

We always enjoy all types of science experiments for kids! Our latest science experiment is all about exploring the surface tension of water and other liquids. This simple experiment for kids really intrigued my 5 year old and inspired her to come up with all kinds of ideas!

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Whenever I  present my kids with science experiments, my main goal is to inspire them to make predictions and critically think about the world around them.  Exploring the surface tension of water and other liquids really motivated Lucy to come up with her own predictions and ideas! (This post contains affiliate links.)

Science Experiments for Kids: Exploring Surface Tension

Materials for Exploring Surface Tension

• Water
• Cooking oil (We used canola oil.)
• Rubbing alcohol (optional)
• Containers to hold the liquids (We used 4 oz Ball jars.)
• Eye droppers
• Toothpicks
• Dish soap
• Wax paper

Procedure

1. Use the eye dropper to place a few drops of water on some wax paper. Observe the drops closely. What do you notice?

2. Use another eye dropper to place some drops of cooking oil near the water drops. Compare the cooking oil to the water. How are they the same? How are they different?

3. Look closely at other liquids like rubbing alcohol on the wax paper. Compare and contrast all the liquids.

4. Try poking the water drop with a clean toothpick. What happens?

5. Now poke the water drop with a  toothpick that has been dipped in dish soap. What happens? Why do you think this happened?

After completing the previous steps, Lucy enjoyed trying out her own ideas. She tried placing drops of oil on top of water drops and tried mixing them together. Then she tried poking the different liquid drops with clean and soapy toothpicks. She was so intrigued!

What’s Going On?

The water drop on the wax paper looks kind of like there’s a skin around it. When you poke it with a clean toothpick, nothing happens, but, when you poke it with a soapy toothpick, the water spreads out.

Drops of water stick to each other. That’s why the surface of the water drops appear to have a skin-like layer on them.  This is called surface tension. Soap decreases the water’s surface tension causing it to spread out.

Want to Go Even Further?

Related activities to extend the learning for various ages.

• Here’s another experiment having to do with the surface tension of water~ Paperclips in Water.
• Try a similar experiment. See how many drops of water can sit on the surface of a penny using a dropper. Was it what you expected?
• Observe how the drops of other liquids look on the wax paper.
• Related Children’s Book: A Drop Of Water: A Book of Science and Wonder

Be sure to check out STEAM Kids book and ebook for even more creative STEM and STEAM ideas!