Lesson 1 of 9
A number for hot
Show on a big screenTwo hands can feel "warm" differently. A number is the same for everyone.
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Step 1 of 4
- The bulb holds liquid. Cool, so the liquid sits low.
- Warm the bulb.
- The liquid expands. It climbs the tube on its own.
- The height gives the number.
The rule
Temperature tells how hot or cold something is. We write it in °C (degrees Celsius).
Most liquids expand when they warm. They take up more room.
A thermometer is a thin tube with a bulb of liquid. The bulb is the round part at the bottom. The tube is sealed, so nothing leaks out.
The warm liquid expands. It has one way to go, so it climbs the tube. The liquid's height gives the number.
Ice water reads 0 °C. Boiling water reads 100 °C. Your body reads about 37 °C.
Try the lab to finish this lesson.