Ultraviolet (UV ) light is invisible radiation that can damage your skin and eyes if you don’t protect yourself. If your kids are anything like mine, they find sunscreen a bit of a sticky inconvenience, so UV beads are a fantastic way to visually demonstrate how sun cream protects our skin from too much UV light.
The beads contain a photochromic dye which changes colour when exposed to UV light. They are clear when inside and change colour when exposed to sunlight.
UV Bead Science Investigation
You’ll need
2 petri dishes, clear containers or transparent plastic bags
Sunscreen
Instructions
Place about 10 UV beads in each petri dish, then cover with the lid.
Take both petri dishes outside. The beads should start to change colour. If they don’t change, try to find a sunnier spot.
Cover one of the petri dish lids with sunscreen. You should find that the beads start to lose their colour or become duller.
What’s going on?
The sun emits different kinds of light, including visible, infrared, and UV light. You can’t see UV light, but it has a lot of energy. UV light can cause sunburn if skin is exposed for too long.
Sunscreen contains ingredients that absorb or reflect UV radiation before it reaches the skin. When used to cover the Petri dish, it blocks UV light from reaching the beads, and so they don’t change colour.
Extension Tasks
Try this activity on a sunny day. You might be surprised to see that the beads will still change colour when it’s cloudy, as UV light can pass through clouds.
Design an investigation to determine whether different SPF sunscreens keep beads clear for longer.
Experiment with a waterproof sunscreen by submerging a plastic bag or petri dish covered in it in water to see whether it affects its effectiveness.
Free UV Bead Investigation Sheet
Don’t forget to take a look at my other summer science experiments.
Last Updated on July 11, 2026 by Emma Vanstone
