BSL Chemistry Glossary - temperature - definition
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Definition: Temperature is a way of measuring how hot or cold something is. When the mercury goes up in the thermometer it's very hot. When it goes down it's cold. When a person goes to hospital they have their temperature taken. The thermometer has red or silver line that shows the temperature. That's actually a liquid inside the glass thermometer. When the thermometer gets heated up by someone's mouth the particles in the liquid start moving around faster and the liquid expands. As it expands the liquid rises up thermometer showing a higher temperature. When the thermometer is cooled down, the particles in the liquid move less and the liquid contracts, so the temperature falls.
reproduced by permission from Hodder