Hello.

Welcome to today's lesson.

We're going to look at measuring temperature today.

We'll look at the unit of measurement involved as well as some types of equipment that we can use to measure temperature.

My name's Mrs. Clegg.

This lesson's part of the heating and cooling unit.

Let's get started.

So by the end of today's lesson, you should feel much more confident in being able to safely and accurately measure the temperature of different objects using a thermometer.

Here are our keywords for today, temperature, degrees Celsius, and thermometer.

Temperature is a measure of how hot or cold an object is.

Degrees Celsius is the unit of temperature, and a thermometer is a device that measures temperature.

Today's lesson's split into two parts.

So we're gonna get started with the first part, using a thermometer.

A temperature is a measure of how hot or cold something is.

So we've got a cup of tea there and an ice cream.

A cup of tea will have a higher temperature than the ice cream.

Temperature can be measured in a unit called degrees Celsius, and this was named after a Swedish astronomer called Anders Celsius in 1742, I believe.

Let's just spend some time thinking about that unit and how to write it properly.

So the degrees symbol is a small circle, and we write it in superscript, and then the C is a capital C for Celsius, and we now know why, because it's named after a person.

I wonder how many places you can find the unit degrees C around your home.

You'll definitely find it on clothes and food, for example.

On the labels of clothes, there's usually washing instructions that tell you how warm the water should be, and you'll find it on cooking instructions, and that helps us to know which temperature to set the oven at, and it's also helpful in terms of storing food.

Let's have a check.

Which of the following is the correct way to write the unit of temperature? Well done if you said b.

That is correct.

Let's think about how to measure temperature now.

We use devices called thermometers.

Let's just have a look at that word thermometer.

So a metre is often an instrument for measuring something, and therm means to do with heat.

So a thermometer is a device for measuring heat, and here we've got three different types of thermometer.

The gun thermometer is quite useful when you don't actually want to touch the object that you want to measure the temperature of.

So it can be pointed at a person, for example, or an animal or an oven, something like that where you don't actually want to touch the object.

And this is really useful in making sure that you don't spread disease, for example.

You might have seen a medical thermometer like this one.

This is a digital thermometer.

You can see the digital reading there, 38.

75 on the image, and you would put the tip under your tongue or armpit, and there are also medical thermometers that you can put in your ear as well.

And then we have the glass thermometer, and a glass thermometer is what we tend to use in the laboratory.

It's what you will tend to use in your science lessons, but they can also be used to measure external temperature of the environment, for example, or in a greenhouse or to measure room temperature, that sort of thing.

Let's look at a glass thermometer in a little bit more detail.

So it's a glass tube with a bulb at the bottom.

The bulb is full of a coloured liquid.

Now, in our diagram, it's coloured red, but you can also get a green-colored liquid or blue-colored liquid in thermometers too.

When the bulb is warm, the coloured liquid rises, and when the bulb is cold, the coloured liquid drops down the tube.

We read the temperature using a scale that's marked on the tube.

So here we can see a temperature of 21 degrees Celsius.

What do you think the reading on this thermometer would be? Well done if you said a, 29 degrees Celsius.

It's not quite at the 30 graduation mark, and it can't be 31 because it's not gone over 30.

So 29 is the right answer.

Well done if you got that correct.

Now, to get an accurate reading, we want to put the bulb of the thermometer inside the object that you're measuring the temperature of.

We need to wait for the coloured liquid to settle, and then we read the scale with our eye at a level of the top of the liquid.

That's the most accurate way to read the thermometer scale.

You can see in the diagram that the thermometer's being held in a clamp on a stand.

What do you think the temperature is on this scale? I think it's 89 degrees Celsius.

Let's have a quick check.

Which would be the best method for measuring the temperature of the sand in the beaker? Let's have a look.

So a is looking pretty good to me.

The bulb is well into the sand.

B, the bulb is pointing up into the air.

So that's not actually measuring the temperature of the sand, is it? And c, the bulb is half in and half out of the sand.

So it's half measuring the sand and the air temperature.

So a is definitely the right answer.

Well done if you've got that correct.

Glass thermometers are very fragile, so we need to store them in a tray when they're not in use to stop them rolling onto the floor or getting knocked off.

It can be really useful to hold a thermometer in between the soft pads of a clamp on a stand when you're taking measurements.

When you're taking measurements, it can be useful to hold a thermometer in between the soft pads of a clamp on a stand, and if we wanted to measure hand temperature, we would put the thermometer between our palms. So let's have a check.

Which of these do you think is the best way to measure the temperature of your your hands? Well done if you said c.

Let's think about taking the temperature of boiling water.

Now, boiling water can burn you, so we need to set up the apparatus safely, and in order to do that, we would set it up before we turn the Bunsen burner on.

We should wear eye protection and keep our face away from steam.

Don't touch any of the apparatus until the hot parts have cooled down, and if you look at that experimental setup, there's lots of places where the equipment will be hot, the Bunsen burner, the tripod, the gauze, the beaker, et cetera.

So wait until it's cooled down.

Let's have a check.

To measure the temperature of the boiling water, when should you put a thermometer into the water? Well done if you said a, before turning on the Bunsen burner.

Let's have a look at Task A now.

We're going to use a thermometer safely to measure the temperature of different things.

There's lots of objects there in the table.

Set up your equipment safely and measure their temperature.

Pause the video and come back when you're ready.

Okay, let's have a look.

So here are some sample results.

Yours might be slightly different.

How do yours compare? Let's move on to the second part of our lesson, common temperatures.

These are temperatures that we might know.

So pure water melts at 0 degrees Celsius, and pure water boils at 100 degrees Celsius, and actually, these are how we know we've got pure water.

Your results might vary a little bit because glass thermometers are not always completely accurate.

Now, have you ever thought about how they put a scale onto a thermometer? So let's have a go.

You put your thermometer with no scale into melting ice and then allow the coloured liquid to settle, and that should be 0 degrees Celsius.

And then you put your blank thermometer into boiling water and mark the 100 degrees Celsius level.

Measure the distance between the 0 degrees C level and the 100 degrees C level using a ruler and then divide by 100 degrees Celsius to work out the distance on the scale that would represent a change of 1 degree Celsius.

So for example, if the distance between 0 and 100 was 10, you would do the calculation 10 centimetres divided by 100 degrees Celsius, and that would equal 0.

1 centimetre per 1 degree Celsius.

And then you can mark those temperatures on your scale.

Let's have a quick check.

So markings at 0 degrees Celsius and 100 degrees Celsius on a thermometer are 20 centimetres apart.

Which statement is now correct? Well done if you said 0.

2 centimetres.

I wonder if you've ever thought about the average temperature on our planet.

Well, it's actually 15 degrees Celsius.

Do you know what the average body temperature of a human being is? Well, our body has a core temperature of 37 degrees Celsius, and our hands would be slightly lower, around about 31 degrees Celsius.

Your results might be slightly different from person to person.

Have you ever thought about what room temperature is? Again, it's usually around about 20 degrees Celsius, and if we leave things for long enough, all the objects in a room will reach the same temperature.

So let's have a quick check.

A room in a house has a wooden door with a metal handle.

Which of the following is true? Well done if you said b.

The wooden door is at the same temperature as the metal handle.

Let's have a look at Task B.

So I want you to draw a diagram of a glass thermometer with a scale that is 20 centimetres long between the 0 degrees Celsius marking and the 100 degrees Celsius marking.

Sometimes it's helpful to draw it on blocked paper or graph paper to help you.

And once you've done that, I'd like you to mark the position of six temperatures of things that you now know.

So for example, we know that melting ice has a temperature of 0 degrees Celsius.

What other temperatures do you know? On your diagram, could you also label the bulb, the glass tube, coloured liquid, and the scale? Pause the video and come back when you're finished.

Welcome back.

How did you do? Let's have a look.

So here's a sample diagram.

So we've got the 0 degrees Celsius and 100 degrees Celsius marked, and then we've got a variety other things marked on there, like a cup of tea is 90 degrees Celsius.

The human body is 37 degrees Celsius.

Room temperature is 20 degrees Celsius.

A fridge is 5 degrees Celsius, and melting ice is 0 degrees Celsius.

Well done, and we've got the bulb labelled and the coloured liquid.

Amazing.

Well done.

So let's have a look at the summary of learning for today.

So thermometers measure temperature in the unit degrees Celsius.

Ice melts at 0 degrees Celsius, and water boils at 100 degrees Celsius, and if we leave it for long enough, all the objects in a room will reach the same temperature.

We know that a thermometer has a bulb.

It's a glass tube that contains coloured liquid, and the glass tube is marked with a scale to help us read the temperature.

And I hope you feel a lot more confident about being able to accurately use a thermometer to measure the temperature of different objects.

Well done.

I look forward to working with you next time.