A thermometer is a tool or instrument used to measure temperature. Thermometers should be handled with care. They are tubes of glass filled with colored alcohol. At the bottom of the tube is a wider part called the bulb. When the bulb is heated, the liquid in the bulb expands or gets larger, causing the liquid to rise in the tube. When the bulb is cooled, the liquid contracts or gets smaller, causing the liquid to fall in the tube. The bulb at the base of the thermometer should be immersed in the material to be measured. To use a thermometer, you must remember the following:

• In science, temperature is measured in degrees Celsius (°C).
• If you are measuring the temperature of a material that is being heated, make sure the thermometer bulb is not resting on the bottom of the container.
• To read the temperature, your eyes should be level with the liquid in the thermometer.
• Determine the increment scale in the same manner you did the graduated cylinder.

You Try!

Determine the temperature on the following thermometers.