Heatwaves teaching resource

Keep cool in a heatwave

 Explore the effects extreme heat can have on our bodies and ways to keep cool in a heatwave with an interactive activity.

Woman cools down on a hot day with a bottle of water
Practical activity
Disasters and emergencies, Home learning resources

Keeping cool science activity

Our clothes can play a big part in keeping us cool, from the material they are made from and even their colour. Try the experiment below to see what effect clothing has on the temperature of water, and learn how to stay cool during extreme heat. Try this science experiment with water to see this in action.

What you'll need:

  • four similar shape and size drinking glasses
  • four different types of materials (cotton, wool, denim, polyester etc) Check the label on your clothes to see what they are made from 
  • a sunny day 
  • a thermometer 
  • pen or pencil and some paper 
  • water 
A photograph of a thermometer showing a high temperature on a very hot day.

Activity instructions

  1. Fill all glasses halfway with water
  2. Use your thermometer to measure the temperature of the water in each of your glasses and take a note of the temperature on your paper.
  3. Take your four water glasses outside, placing them in a nice sunny spot.
  4. Wrap each one of your glasses surrounding the sides and top with a different type of material. For example, you could use a cotton tee-shirt on one, a woolly jumper on another, a pair of denim jeans on the third, and the last one could be wrapped up with a polyester sports top.
  5. Leave them in the sun for one hour. During this time, predict what changes you think will happen to the water. Write down your predictions on your piece of paper.
  6. After the hour, unwrap the clothes from the glasses of water, being careful not to knock them over or spill any of the contents.
  7. Using your thermometer, measure the temperature of the water now, and write down your results.

Discoveries and next steps

What did you notice, was there a change in temperature? Did you notice any other changes? Compare the water levels of the glasses, did any of the water in the glasses evaporate?


The type of clothes we wear on a sunny day can have quite a considerable effect on our body temperature, especially during heatwave weather. The colour of our clothes can have an interesting effect too. Try the experiment again but this time use four tee-shirts, made from the same material.


What did you notice this time?

Lighter coloured materials will reflect more of the sun’s rays which will help you stay cool. Darker colours will absorb those rays which will increase your body temperature.

Share your results with us on social media, tag us @britishredcross and let us know what you discovered.

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