# Lesson Video: Reading Thermometers Mathematics

In this video, we will learn how to measure temperature in degrees Celisus with a thermometer and specify whether the temperature is cold, cool, warm, or hot.

11:09

### Video Transcript

In this video, we will learn how to measure temperature in degrees Celsius using a thermometer and say whether it is cold, cool, warm, or hot.

We use a thermometer to measure temperature. If you’ve ever been ill and visited the doctor, maybe you’ve had your temperature taken. A thermometer can tell us how hot or cold we are. Sometimes when we’re ill, our bodies get too hot. Doctors can give us medicine to help our temperature go back to normal.

We can also use a thermometer to tell us how hot or cold it is outside. Thermometers contain a special liquid. And when the liquid heats up, it rises. This is a hot day. The temperature is 30 degrees Celsius. We can measure temperature in degrees Celsius.

Thermometers have a scale. It looks just like a number line. We read the scale in the same way we would read a number line. We use it to help us read the temperature. We find the level of the liquid inside the thermometer, and we read across to the scale to find the temperature. When the temperature is zero degrees Celsius, we often say it’s freezing. It is very cold because at zero degrees Celsius, water freezes. We know if the temperature outside is zero degrees or below zero degrees, it’s very cold.

On a hot day, the temperature is usually above 30 degrees Celsius. 10 degrees Celsius would probably be a cool day. We’d probably need our coats. And if the temperature was 20 degrees Celsius, we’d probably say it was a warm day.

Not all thermometers are the same. The scale on this thermometer goes up in 10s. Zero, 10, 20, 30. The scale could go up in twos, or even in 20s. We need to be very careful when we’re reading the scale. Let’s have a go at some questions now and practice reading thermometers.

Jennifer, Liam, and Daniel are in different parts of the world. Find the thermometer that shows what the temperature is where they are.

This is Jennifer. And she’s saying, “It is cold here.” We have to find or choose the thermometer that shows what the temperature is like where Jennifer is. Which of the three thermometers shows the temperature is cold? Let’s read the temperature on all the thermometers to try and find the one which shows that it’s cold.

The temperature on the first thermometer is between 10 and 20 degrees. Halfway between 10 and 20 degrees is 15. And we’re two marks past 15. Two more than 15 is 17. The temperature on the first thermometer is 17 degrees Celsius.

Let’s read the temperature on the second thermometer. It’s somewhere between 30 and 40 degrees Celsius. The red line shows 35 degrees. And our temperature is two marks below 35. Two less than 35 is 33.

The temperature on the third thermometer is really easy to read. It’s at zero degrees Celsius. Which of these temperatures shows that it’s cold outside? 17, 33, or zero? It’s this thermometer. When it’s zero degrees Celsius, it’s cold outside. This is the thermometer that shows the temperature where Jennifer is.

This is Liam. He says, “It is hot here.” Which thermometer shows the temperature where Liam is? We know it’s not the third thermometer because it shows zero degrees Celsius. That’s the temperature where Jennifer is. We’ve already read the thermometers, and we know the first one says 17 degrees Celsius. And the second thermometer shows 33 degrees Celsius. Which is hotter? 33 degrees or 17? It’s 33 degrees Celsius. This is the thermometer that shows the temperature where Liam is.

This is Daniel. He says, “It is warm here.” We know that this thermometer shows the temperature where Jennifer is. It’s cold where Jennifer is, and it’s zero degrees Celsius. And we know that this thermometer, which shows 33 degrees Celsius, which is hot, is the thermometer that shows the temperature where Liam is. So, the thermometer that shows the temperature where Daniel is must be the first one, which shows a temperature of 17 degrees Celsius. So, this is the thermometer that shows the temperature where Daniel is. 17 degrees Celsius is warm.

So, this is the thermometer that shows the temperature where Jennifer is. Zero degrees Celsius is cold. This is the thermometer that shows the temperature where Liam is. 33 degrees Celsius is hot. And this is the thermometer that shows the temperature where Daniel is. 17 degrees Celsius is warm.

Which thermometer shows 15 degrees Celsius?

In this question, we’re shown three different thermometers. We need to read the thermometers to find the one which shows 15 degrees Celsius. The level of the liquid in the first thermometer is level with the number 10 on the scale. This thermometer shows 10 degrees Celsius. Which temperature does the second thermometer show? Two marks above 20 is 22 degrees Celsius. This isn’t the thermometer we’re looking for either. Let’s see if the last one shows 15 degrees Celsius.

The level of the liquid in this thermometer is halfway between 10 and 20, which is 15 degrees Celsius. This is the thermometer we’re looking for. It shows 15 degrees Celsius.

These thermometers are different. Look carefully and find which thermometer shows the coldest temperature. Which thermometer shows the hottest temperature?

Like the question says, we need to look carefully at the scales on each thermometer. The scale on the first one goes from zero to 10. Each of the divisions on this scale is worth one. Let’s read the temperature. Zero, one, two, three, four. The temperature shown on thermometer A is four degrees Celsius.

The scale on the second thermometer is between zero and 50. The numbers marked on this scale go up in 10s. Zero, 10, 20, 30, 40, 50. And the marks or the divisions in between each multiple of 10 are worth five because half of 10 is five. Zero, five, 10, 15, 20, 25, 30, 35, 40, 45, 50. This scale goes up in fives. The temperature on this scale is between 35 and 40, probably around 37 degrees Celsius.

Let’s read the third thermometer. The scale goes up in 10s. Zero, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100. The liquid on this thermometer is level with the halfway mark between 40 and 50. Halfway between 40 and 50 is 45 degrees Celsius.

Now, we know what the temperature is on each thermometer, we can find the coldest temperature, and the hottest. Which thermometer shows the coldest temperature? It’s thermometer A. Four degrees is colder than 37 degrees and 45 degrees Celsius. And which thermometer shows the hottest temperature? It’s thermometer C. 45 degrees Celsius is hotter than 37 degrees and four degrees. The thermometer that shows the coldest temperature is A. And the thermometer which shows the hottest temperature is C.

What have we learned in this video? We’ve learned how to read the temperature on a thermometer in degree Celsius and how to tell whether it is cold, cool, warm, or hot.