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Keeping warm

What's the big idea?

Temperature is a measure of how warm or cold things are. A red-hot pin is at a higher temperature than a kettle of boiling water - although there's a lot more heat in the kettle. We measure temperature in degrees, named after a scientist called Anders Celsius - degrees Celsius or oC.

Thermometers measure the degree of heat. They contain a liquid that expands - swells - as it gets hotter. The tube of the thermometer holds in the liquid, so that it pushes its way up the tube. You can read the temperature from a specially made scale on the side.

Heat travels. But you can slow the movement of heat with a material called an insulator. Air is a good insulator. Materials which hold a lot of air - like thick woolly blankets - also slow the movement of heat. Materials like this - good insulators - can slow the movement of heat out of something - so we use oven gloves to protect our hands from the heat of a hot casserole - and also into something - so wrapping ice cream in newspaper will slow down the rate at which it melts.

Keeping warm