Bubble geometry experiment to try with your child

A soap bubble is simply a very thin sheet of soapy water, called a soap film, surrounding a volume of air.

A force called surface tension pulls the soap film tight, so that it always has the minimum surface area possible. That's why a free-floating bubble always forms a sphere.

This experiment, brought to you in partnership with the Science Museum Group, is a fun and easy way to help your child understand the science behind shapes and their properties.

As this activity involves lots of water, you should do it in a place you don't mind getting wet and that you can clean up easily afterwards. Doing it outside is doable but even a small amount of wind might affect the bubbles that you make!

Instructions for you and your child to follow…

You will need

• Washing up liquid
• Warm water
• Scissors
• A protractor (you could print our template here)
• Bucket or a large bowl
• Sugar
• Clear plate or a clear lid
• Five straws (with four straws cut into three even pieces)
• Nine pipe cleaners

Let's get started

Step 1

Add 3/4 of a mug of sugar and a whole mug of washing-up liquid to 3/4 of a bucket of warm water and stir the mixture slowly for a minute or two.

Step 2

Slide the protractor underneath the clear lid or plate. Lightly coat the surface of the lid with bubble mix, dip the straw into it and slowly blow bubbles.

Step 3

Move the lid, so you can measure the angles of the bubbles on the protractor.

Have a look at the bubbles. "Are all of the angles the same?" "Can you blow a bubble inside another bubble?"

Did you know… whenever two or more bubbles meet, the angle between them will always be exactly 120 degrees?

Now to make a cube bubble

Step 4

To make a cubic frame, fold a pipe cleaner to give it three loops. Put one piece of straw on each loop.

This becomes one corner of the cube.

Step 5

Make seven more pipe cleaner corner pieces, and attach more straw pieces to complete the cube.

Step 6

Dip the frame fully into the solution. Gently pull it out and blow a bubble in the middle with a straw.

Maths in your world

The hexagon pattern seen in honeycomb works in the same way as how bubbles connect – always at 120 degrees. The honeycomb connects using the least amount of wax.

The Science Museum Group is a group of museums in the UK who share objects, stories and hands-on activities to engage more people in science, technology, engineering and maths.

Images © Science Museum Group

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