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# Science Sunday: Blowing bubbles to explain surface tension

This time of year, who doesn't have bubble solution laying around?

CHARLOTTE, N.C. — Have you ever seen small insects walking on water? Or maybe a magic trick where a needle floated in a cup of water?

Well, the ability for these things was all caused by surface tension… or rather, not breaking the surface tension of water.

This is an easy and safe way to explain surface tension to your kiddos and just have some summer-like fun!

### What you’ll need:

• Bubble solution in a cup
• Spray bottle with water
• Flat surface
• Straws

Step 1: Set up everything on your flat, dry surface

Step 2: Test out your bubble

Dip your straw in the bubble solution and try to blow a bubble on your dry surface. You’re able to blow one, but it pops quickly!

Repeat Step 2 but notice how much bigger your bubble gets. And it lasts much longer!

Step 5: Try popping it yourself!

Touch it with your finger. It pops, right? Well, repeat Step 4 and dip your finger in water. What happens now? It doesn’t pop!

### How does it work?

Bubbles are made with soap and water. A bubble pops when the water evaporates and makes it too thin, so it’s subject to your finger making it go poof.

However, when you add water to the flat surface or dip your finger in water, you’re maintaining the surface tension - allowing the bubble to stay in place.

This is similar to when you take a bubble bath and the bubbles stick to your body!

### What is surface tension?

Surface tension is defined as the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the water molecules.

The shape of rain droplets, the shape of bubbles, and the beading of rain on a waxy surface are all real-world examples of surface tension, too.