Bubbles! We all know how fascinating they are, evoking happy memories of blowing and chasing the mystical orbs with our friends. A bubble’s fragile nature, beautiful rainbow colors, and ability to soar through the sky make them universally fascinating among kids.
What is the science behind (or inside) a bubble? Bubbles can provide a fun way to study science concepts such as elasticity, surface tension, chemistry, light, and even geometry. Your students can engage in processes such as observation, experimentation, investigation, and discovery, simply by studying bubbles.
For starters, here is a fun demonstration that you can perform as you explain some of the science of bubbles. Follow the recipe at the end of this article to make some super strong bubbles for your act. Wearing a clown suit is optional.
Blow a bubble, get a few laughs. Then talk about what makes a bubble.
Bubbles are just air wrapped in soap film. Soap film is made from soap and water (or other liquid). The outside and inside surfaces of a bubble consist of soap molecules. A thin layer of water lies between the two layers of soap molecules, sort of like a water sandwich with soap molecules for bread. They work together to hold air inside.
Create a bubble that stretches out using a large wand (that you can make from a piece of wire). Whoosh it through the air so the bubble follows and grows behind it. Then, with great drama, let the bubble go. Give the students a chance to note what happens to it before it pops.
Why is a bubble round? Bubbles can stretch and become all kinds of crazy looking shapes. But if you seal a bubble by flipping it off your wand, the tension in the bubble skin shrinks to the smallest possible shape for the volume of air it contains. That's why even if it had a goofy shape before you sealed it, once sealed shut, the bubble will shrink into a sphere shape. Compared to any other shape, a sphere has the smallest surface area for the amount of volume.
Blow several bubbles and have the students blow and fan them to keep them from landing. The object here is to watch them pop without obvious interference. And it’s a bit of fun for everyone.
Why do bubbles pop? Other than being poked or landing on something sharp, bubbles pop when the water between the soap film surfaces evaporates. To note, when it’s cold, those molecules take longer to leave. If you blow a bubble on a calm winter day, a bubble can even freeze and last for several minutes before it wisps away.
Also, the colder the outside temperature is, the higher a bubble might fly. That’s because the warm air from your breath is lighter than cold air.