Science At Home! Water Tension Experiment

For immediate release ‐ April 01, 2020

Contact: Jessica Wackes, 919.707.9850. Images available upon request

Are you looking for something to do to keep your brain active and engaged? We’re here to help with Science at Home! Over the next few weeks, we’ll be providing you with fun science experiments you can conduct using commonly found items. You can also visit us at the Museum’s Science at Home page for additional resources! Find a print-out version of this experiment here!

Materials Needed

  • Large bowl
  • Dish soap
  • Black pepper
  • Needle or straight pin
  • Water
  • Optional items: paper clip, tweezers

Experiment Instructions

Pouring water into bowl.

Step 1: Fill the bowl with water. Wait until water is still.

Float a needle on the water surface.
Step 2: With care, place a needle or straight pin on the surface of the water without sinking it. Tip: avoid touching the water with your fingers (this is where the tweezers will come in handy).

Carefully placing a paperclip on the surface of the water using tweezers.

Optional Step: If you are successful with the needle or pin, really challenge yourself by trying to float a paperclip!

Sprinkling water surface with ground pepper.

Step 3: Remove objects from water. Then, sprinkle black pepper across the surface of the water.


Placing a small amount of dish soap on fingertip.

Step 4: Place just a bit of dish soap on your fingertip.

Touching fingertip to pepper-covered water surface.

Step 5: Touch the tip of your finger in the center of the pepper-covered surface and watch what happens!

What We’ve Learned

Water forms a skin-like surface called water tension. This occurs because the water molecules at the surface are pulled closer together than the ones directly below the surface.

Natural Connections

Water striders on water surface. Photo by hao wang on Unsplash.Photo: hao wang on Unsplash.

Water Striders are insects that exploit this property of water living their entire lives in this unique environment between air and water.

Another insect, a species of Rove Beetle, uses a surfactant (similar in action to the dish soap you used). When threatened, the insect dips its abdomen into the water and exudes a drop of surfactant which interferes with the water tension. The beetle is then quickly propelled by the expanding edge away from a hungry predator, just like the pepper!

Having Fun?

We want to see! Tag @naturalsciences on social media so we can see you and your loved ones enjoying our Science at Home experiments.

Want More Experiments?

Try this one about Water Density!

Try making a rubber egg!

For more information about our upcoming activities, conservation news and ground-breaking research, follow @NaturalSciences on InstagramTwitter and Facebook. Join the conversation with #visitNCMNS.

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