Our astronaut William Anders must keep warm when he is in space. NASA spent a long time designing and making materials that would keep heat in and stop astronauts getting cold. A material that does not let heat pass through easily is called a THERMAL INSULATOR. Click on the button below to try an online experiment with thermal insulators. When you have looked at it, think about how you could set up the same experiment in your classroom. Scroll down the page for more ideas to help you