Lesson video

Hello there.

How are you today? What is the most interesting thing that you have learned today? That is interesting.

Today we have another science lesson.

This time we are going to learn about what happens when we heat a substance up or cool it down.

Are you ready? Let's get started.

In today's lesson we're going to start by recapping our previous knowledge.

We will then find out what happens to particles during heating and cooling.

And then look at some specific examples.

For this lesson you will need an exercise book or paper and a pencil.

If you don't have one of these items, pause the video now and go and get them.

Let's recap our previous knowledge.

Can you remember the three states of matter? The three states of matter are solids, liquids and gases.

Can you remember the properties of solids? Pause the video now and write down three properties of solids.

Solids cannot be compressed, they do not flow and they have a fixed shape.

Can you remember the properties of liquids? Pause the video and write down three properties of liquids.

Liquid cannot be compressed, they can flow and they can take the shape of the bottom of their container.

Can you remember the properties of gases? Pause the video and write down three properties of gases.

Gases can be compressed, they can flow and they can fill the shape of their container.

Point to the diagram that shows a solid.

How do you know? The diagram on the left shows the solid.

We know it's a solid because the particles are arranged in ordered rows and they're all touching.

What is the difference between the particles in the liquid and the particles in a gas? Particles in a liquid are touching, whereas particles it a gas are far apart.

Pause the video and draw lines to match the description to the correct state of matter.

Press play when you're ready to hear the answer.

In solids, particles are touching and in ordered rows.

In liquids, the particles are touching and in a random order.

In gases, particles are far apart from each other.

Pause the video and draw lines to match the description to the correct state of matter.

Press play when you're ready to hear the answer.

In solids, particles cannot move, but they can vibrate on the spot.

In liquids, the particles can slide past each other, and in gases, the particles are moving constantly in all directions.

Let's find out what happens to the particles during heating.

I have a problem.

This jar of jam.

It's a nice jar of homemade jam.

The lid is stuck on.

It's really hard to open.

I really can't open it.

No matter how hard I try.

To help me open it, I'm going to place my jar under hot water.

Let me go do that.

I've just placed my jar under hot water to help me open it.

Let's try again and see if I can open the jar.

That was so much easier.

After I put the jar under hot water, it was easier for me to open the jar.

I wonder what happened.

When I place the lid in hot water, the lid expanded.

That means the lid got bigger.

My turn, expanded.

Your turn.

When we heat substances up, they expand.

They get bigger.

When I put my jar in hot water, the lid expanded it, making it easier to remove.

Let's have a look at what happens when we heat other substances.

Here I have a kettle full of hot water.

The water is very hot.

This is not an example of something that you should do by yourself at home.

When I put the hot water into my cup, I'm going to place in a thermometer.

If you look carefully at the thermometer, you should see a red liquid.

I will need to watch what happens to the red liquid when I put it in the cup of hot water.

Can you see the red liquid expanding? The red liquid is travelling up the thermometer because it's getting hotter and it's expanding.

When I place my thermometer in the hot water, the liquid inside the thermometer expands.

Particles in a solid are vibrating in a spot.

When we increase the temperature, they vibrate more.

This causes the substance to expand.

Particles in a liquid can slide past each other.

When we increase the temperature, the particles have more energy and the substance expands.

Particles in a gas are moving fast in all directions.

As we increase the temperature, the particles have more energy.

They move faster and the gas expands.

What happens to the particles when we increase the temperature? When we increase the temperature, the particles have more energy.

What happens to the substance when we increase the temperature? When we increase the temperature, the substance expands.

Pause the video and fill in the gaps on this slide.

Press play when you're ready to hear the answer.

When we increase the temperature particles have more energy and the substance expands.

Now let's think about what happens during cooling.

I want you to imagine I have a balloon.

If I put my balloon in ice cold water, the balloon would shrink.

This is because the gas inside the balloon contracts when it gets cold.

When we place a balloon full of air in cold water, the gas contracts.

My turn, contracts.

Your turn.

What does the word contract mean? Contract means get smaller.

The gas contracts making the balloon smaller.

What happens to the substance when we increase the temperature? When we increase the temperature, the substance expands.

What happens when we decrease the temperature? The substance contracts.

Expands.

Contracts.

Increasing temperature, decreasing temperature.

Let's have another look at the thermometer.

So this time I'm going to put my thermometer into cold water.

I want you to watch what happens to the red liquid as I move it from hot water to cold water.

Can you see the red liquid travelling down? The liquid is contracting because the temperature is decreasing.

When I place my thermometer in cold water, the liquid inside the thermometer contracts.

What does the word contract mean? The word contract means gets smaller.

Particles in a solid are vibrating on the spot.

When they get colder, they vibrate less.

In a liquid they're sliding past each other.

When they get colder, they move slower.

Particles in a gas are moving fast in all directions.

When they get colder, they move slower.

As a result, when we decrease the temperature, the particles have less energy and the substance contracts.

Pause the video and fill in the gaps in this sentence.

Press play when you're ready to continue.

When we decrease the temperature particles have less energy and the substance contracts.

Let's look at some examples.

How could heating and cooling be useful? Pause the video to copy and complete the table.

You are going to look at putting a jar under the hot tap to help get the lid off, using liquid in a thermometer to help you tell the temperature and cooling oxygen and hydrogen to put them into tanks.

Press play when you're ready to continue.

When we put a jar under the hot tap heating the lid is helpful because the lid expands making it easier to remove.

Heating the liquid in a thermometer when you place it in something hot is helpful because the liquid expands so you can find out the temperature.

When storing gases like oxygen and hydrogen cooling them is helpful because it means they may take up less space.

Pause the video to tick or fix your answers.

Why might it be dangerous to heat a gas when it is trapped in a metal can? Have a think.

What do you think? Why might it be dangerous? What's going to happen to the gas when you heat it? When you heat a gas it expands.

So if it was trapped inside a metal can and the gas expanded, it's going to explode the can.

That's why it's dangerous.

You have worked so hard today.

I'm really impressed with everything you've learned about heating and cooling substances.

We've learned that when you heat a substance it expands and when you cool a substance it contracts.

I'm looking forward to seeing all of your hard work on the quiz in a minute.

See you next time.

Bye!.