Lesson video

Hello again.

My name is Miss Couves, and I'm really looking forward to our science lesson today.

Recently, I've been thinking about all those fuels we have been burning to heat our houses, drive our cars, and generate electricity to power all of our devices.

Can you remember which pollutant was produced in every combustion reaction? Carbon dioxide.

What is happening as a result? All that extra carbon dioxide? Well, that is what we're going to think about today.

Today, we are going to start by recapping our prior knowledge about the Earth's resources and sustainability.

Then we are going to learn about greenhouse gases and their effect on the environment.

Finally, we are going to look at some data to determine the effects of humans on the environment.

For today's lesson, you will need an exercise book or paper, and a pencil.

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

Let's start by recapping our previous knowledge.

Pause the video and see how much of this slide you can remember.

A natural material comes from a plant, an animal, or the ground.

Our example of a natural material from a plant was cotton.

Our example of a natural material from an animal was wool.

And our example of a natural material from the ground was crop.

Can you think of any other natural materials? Coal was an example of a particular kind of natural resource called a fossil fuel.

What was the problem associated with using fossil fuels? They take millions of years to form, so they are finite resource, which means they are running out.

They also produce carbon dioxide, which is a pollutant.

What's a pollutant? A pollutant is a material that causes a negative impact on the environment.

Let's think about synthetic materials.

Pause the video and see how much you can remember about synthetic materials.

A synthetic material is a material that is made by humans.

Our examples of synthetic materials were glass, ceramics, and plastics.

Because synthetic materials are made by humans, they tend to take a long time to break down in the environment.

Can you remember how long it took a plastic bottle to break down in the environment? It takes 450 years for a plastic bottle to break down in the environment.

450 years! That's a really long time.

We need to be really careful about throwing that kind of resource away.

Because synthetic materials take so long to break down in the environment, they can exist for a really long time in landfill sites.

Can you remember the problems associated with landfill sites? Firstly, they're not very nice to look at.

Secondly, they produce harmful toxins.

And thirdly, they produce harmful pollutants.

In this unit, we've been thinking about sustainability.

Sustainability is meeting the needs of the present, so us now, without sacrificing the ability of future generations, people in the future, to meet their needs.

What were the three R's that scientists use to help us become more sustainable? Reduce, reuse, and recycle.

An example of reducing is reducing packaging.

Lots of shops are trying to stop giving you lots and lots of packaging when you buy fruits and vegetables.

Instead, you can just put the fruit and vegetables straight into your basket.

This reduces the plastic that is completely unnecessary.

What about reusing? What sorts of items can we reuse? Well, we can reuse water bottles, we can reuse coffee cups, and we can reuse plastic bags.

In fact, some shops are even giving you money off if you reuse items, to help us be more sustainable.

Finally, recycling.

What kind of items can we recycle? Recycle lots of items. We can recycle wood, we can recycle paper, we can recycle plastic.

But how do we know if we can recycle an item? That's right.

We need to look for the green recycling logo that's on the back of the packaging.

Scientists use life cycle assessment to assess the environmental impact of an item.

What three things do scientists need to consider when doing a life cycle assessment? They need to consider how it is made, how it is used, and how it is disposed of.

Can you remember how many times you need to reuse your coffee cup to make it more sustainable than using a takeaway cup? That's right, you need to use it at least 20 times before it becomes more sustainable than using a disposable coffee cup.

What about fuels? What is a fuel? A fuel is substance that can be burnt to release energy.

An example of a fuel is a match.

When I light my match, it burns the wood, and releases energy.

Wood is an example of a fuel.

There are three fossil fuels.

Can you remember their names? Coal, crude oil, and natural gas.

What are the two problems associated with fossil fuels? Fossil fuels are a finite resource, which means they're going to run out, and they also produce a pollutant, carbon dioxide.

What does the word combustion mean? Combustion is the scientific word for burning.

Scientists represent combustion reactions using a word equation.

What goes on the left hand side of an arrow in a word equation? The reactants, the things you start with, go on the left hand side of the arrow.

What goes on the right hand side of the arrow? The products, the things that are produced in a reaction.

In a combustion reaction, a fuel reacts with oxygen from the air to produce carbon dioxide and water.

Pause the video and write down the word equation to the combustion of the fuel wood.

Wood plus oxygen produces carbon dioxide plus water.

What are the reactants in the combustion of wood? The reactants in the combustion of wood are wood and oxygen.

What are the products in the combustion of wood? The products in the combustion of wood are carbon dioxide and water.

Finally, what is a pollutant? A pollutant is a substance that has a negative impact on the environment.

Carbon dioxide, which is produced by the combustion of fuels is a pollutant.

What sort of effect does carbon dioxide have on the environment? It's a pollutant, so it has a negative effect on the environment.

We're going to find out about the negative impact of carbon dioxide in our lesson today.

That was a lot of previous knowledge.

Well done for remembering all of that.

Now we're going to find out some new information about greenhouse gases.

Today, we are going to look at the effect of greenhouse gases on our environment.

Have you ever stood in a greenhouse before? What about a room made of glass? What does it feel like? When the sun is out, it usually feels really warm inside a greenhouse.

In fact, greenhouses are used to keep plants warm to help them grow.

Carbon dioxide is called a greenhouse gas.

What do you think carbon dioxide might do to the Earth? A greenhouse gas such as carbon dioxide traps heat, keeping the Earth warm.

Without greenhouse gases, the Earth would be too cold to sustain life.

So, carbon dioxide traps heat, keeping the Earth warm.

Why is carbon dioxide called a greenhouse gas? Carbon dioxide is a greenhouse gas because it traps heat, keeping the Earth warm, but what happened if there was no carbon dioxide in the atmosphere? Well, the greenhouse gases are responsible for keeping the Earth warm enough to sustain life, so without carbon dioxide, the Earth would be too cold and there would be no life.

Have a go at testing your knowledge.

Try answering these three questions in your notes.

I'll read them to you and then you can pause the video.

Number one.

Which gas is responsible for keeping the Earth warm? Number two.

What does a greenhouse gas do? And number three.

Why are greenhouse gases important? Pause the video now.

When you're ready, press play to see the answers.

Carbon dioxide is the gas that is responsible for keeping the Earth warm.

Number two.

A greenhouse gas traps heat.

And number three.

Greenhouse gases are important because they keep the Earth warm enough to sustain life.

So, it sounds like carbon dioxide is pretty important.

It keeps the planet warm enough to sustain life, but I told you that carbon dioxide was a pollutant.

What does the world pollutant mean? A pollutant is a substance that has a negative impact on the environment.

So what's the negative? Well, let's have a think.

Combustion reactions produce carbon dioxide.

The more combustion we do, the more carbon dioxide that is produced.

What do you think the effect of more carbon dioxide might be? Pause the video and write down the products of combustion.

Let's think more about the idea of more carbon dioxide.

Human activity releases more carbon dioxide into the air.

As a result, more heat is trapped, and that increases the global temperature, which means that the temperature of the Earth gets hotter.

So the more carbon dioxide, the more heat that's trapped, increases the temperature.

Ah, so this means it could get hotter, and hotter, and hotter.

I can see why that would be a problem.

What are humans doing to contribute to the increasing amount of carbon dioxide in the air? Human activity such as burning fossil fuels releases carbon dioxide.

What happens if there is more carbon dioxide in the air? So, more heat is trapped, and therefore the global temperature rises.

Let's have a go at recapping our knowledge.

There are three questions for you to answer.

I'm going to read them to you, then you can pause to complete the questions.

Question number one.

What is happening to the amount of carbon dioxide in the air? Number two.

How are humans causing this? Number three.

What is happening as a result? Pause the video to complete the questions.

Press play when you're ready to continue.

Number one.

The amount of carbon dioxide in the air is increasing.

If you wrote that, you can give yourself a tick.

If you didn't, you can correct your answer in a different coloured pen.

Question two.

Humans are causing this by burning fossil fuels to generate electricity and drive cars.

There's one other thing that we're doing when we burn fossil fuels.

What else might we be doing? Yes, we burn fossil fuels to heat our homes.

Question three.

As a result of the increasing amount carbon dioxide, the global temperature is rising.

This is called global warming.

So remember, the more carbon dioxide, the more heat that's trapped, the higher the global temperature.

So, if I've told you that global warming is happening, but we are scientists, so we want to see some evidence for this, and that evidence is going to be in the form of a graph.

Let's have a look at this graph.

The graph shows the average temperature on the Y axis, and the year on the X axis.

Point to the Y axis.

What does the Y axis represent? The Y axis represents the average global temperature.

Point to the X axis.

What does the X axis represent? The X axis represents the year.

What is happening to the average global temperature from 1860 to 2000? The average global temperature is increasing.

How does this provide evidence for global warming? So we know that global warming is the increase of the global temperature.

Does this graph show us that the global temperature is increasing? Yes, it does.

So it's evidence that the temperature is increasing.

But does it tell us that carbon dioxide is the reason for this? No, this specific graph doesn't tell us that carbon dioxide is the reason for this.

We know that because scientists have looked at other evidence and come to that conclusion.

But it's really important when we look at evidence that we know what it is telling us, and what it isn't telling us, because what it isn't telling us, we need to go and find more information about.

How is the amount of carbon dioxide related to human activity? Human activity such as burning fossil fuels releases carbon dioxide into the environment.

The more carbon dioxide, the more heat that's trapped, the higher the global temperature.

Have a go at testing your knowledge by answering the three questions on this slide.

You should use the graph to help you.

Pause the video to answer the questions and press play when you're ready to carry on.

This graph tells us that the average global temperature is increasing.

The graph provides evidence that the global temperature is increasing because we can see as we go from 1860 to 2000, the global temperature increases from 13.

5 degrees to 14.

4 degrees.

Humans could find different ways of generating electricity that don't produce greenhouse gases.

Can you think of any ways that humans can produce electricity without burning fossil fuels? Humans have found lots of ways to generate electricity without burning fossil fuels, including using solar power, which is using energy from the sun, wind power, which is using energy from wind, and hydroelectric power, which is using energy from water.

What three other resources can be used to generate electricity? Solar, wind, hydroelectric or water.

My big question for today is why do you think humans have not changed their behaviour very much to stop global warming? So we know that global warming is happening, we know that it's our fault, and we've known that for a really long time, but we haven't changed much.

We're still driving cars that burn fossil fuels, we're still burning fossil fuels to heat our homes, and we're still burning fossil fuels to generate electricity.

This is a question you can discuss with people at home.

You've worked so hard today.

Well done on all of your learning.

Make sure you do the quiz to practise remembering all of that key information.

See you next time.