Measuring the temperature of water

Now measure the temperature of warm water in a beaker with a laboratory thermometer. The correct way:

• The bulb must be in the water but must not touch the bottom or the sides of the beaker.
• Hold the thermometer upright (vertical), not tilted.
• Read it while it is still in the water.
• Keep your eye level with the top of the liquid column.

Dip the thermometer so that the bulb is in the water, and watch the column rise. Wait till it stops rising, then note the temperature. Do not wait too long, or the water itself will start to cool.

Why read it in the water? Because as soon as you take the thermometer out, the column starts to fall, and the reading would be wrong. (A clinical thermometer is different: you read it after taking it out of your mouth.)

When Phiban and her classmates measured the same boiling water, their readings were a little different. One possible reason: maybe not all of them followed the correct way of reading it.