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Is there anything more fun to play with on a warm day than bubbles? Join us as we explore the bubble science by investigating surface tension.

Want to duplicate this experiment at home or in your classroom? Watch the video for an overview, gather the materials listed at the right, and follow the instructions below!

Required Materials

  • dish soap
  • water
  • 2 straws
  • 2 cups
  • pipette
  • quarter

Step-By-Step Instructions

Step 1

Fill one cup with water and then fill another cup with a mixture of soap and water.

Step 2

Use one straw to blow air into the cup filled with water. Do not drink from the straw. Note how long the bubbles last in the cup before they disappear! They are able to form due to surface tension – the attraction of the water molecules to each other.

Step 3

To illustrate this further, use the pipette to drop some of the plain water onto the surface of the quarter. Note how a dome-like shape starts to form on top of the quarter. Just like the bubbles in the cup of water, this is due to surface tension!

Step 4

Now, blow air through the straw again, but this time into the cup filled with soapy water. Remember not to drink from the straw. Note how long the bubbles last in the cup before they disappear! Longer-lasting bubbles are possible as the addition of soap to the water decreases surface tension, allowing the attraction between the water molecules to stretch and hold air longer than the bubbles formed without soap!