Lesson video

Hi everyone.

My name is Miss Reid and welcome to a new Geography unit which is titled, Mountains, Volcanoes and Earthquakes.

I'm so excited to get started.

Let's have a look at our key question for today.

So our question for this first lesson is, what is the earth made of? Well, in this lesson, we are going to be learning about the structure of the earth, what the earth is made of and where volcanoes and earthquakes occur and why.

So for this lesson, all you'll need is, an exercise book or a piece of paper, a pencil and your brain.

Please take a moment now, to clear away any distractions, including turning off the notifications or apps or conversations that you have running in the background, if you know how to.

Finally if you can, try to find a quiet place where you won't be disturbed during the lesson.

Pause the video now so you can get the things you need and find a quiet place to work.

Excellent.

Now you have everything you need, let's carry on.

So we are Geographers.

Now Geographers are types of scientists who study the earth and that's what we're going to be doing throughout this unit.

This includes, the land, the physical features such as mountains and it includes the people who live within the land and that is, the human features.

And that's, everything that affects or impacts human beings.

So, throughout this lesson, we're going to be thinking about the structure of the earth, then we're going to be asking the questions, what is the earth made of and where do earthquakes and volcanoes occur and why? So, here is the structure of the earth.

Now the earth is a sphere.

It is made up of four main layers and these are, the inner core.

My turn, your turn.

Inner core.

I can't hear you.

Say it a bit louder.

Excellent.

Outer core.

Mantle.

Crust.

Let's recap those again.

I want you to say them with me this time.

Are you ready? Inner core.

Outer core.

Mantle.

Crust.

I think you know them.

So, here is a task for you.

I would like you to sketch this diagram of the earth structure and label the diagram correctly, using the labels on the page.

Now, don't worry if you don't have colours, that's perfectly okay.

You can sketch this with a pencil and then label it.

If you do have colours and you want it colour it in, that's also absolutely fine.

Pause the video now, so you can sketch this diagram and label it correctly.

Have you managed to draw your diagram? Excellent work.

Let's see if you've labelled your diagram correctly.

So you should have labelled, the inner core, the outer core, the mantle and the crust.

Pause the video now so that you can check that you've labelled your diagram correctly.

Great.

Now you've checked, we can move on.

So we're now going to think about what the earth is made of and we're going to break it down into the four different layers.

We're going to go into a little bit more detail on each.

So we'll start with the inner core.

Now, the inner core is made from a mixture of solid metals and these metals are called, iron and nickel.

My turn, your turn.

Iron and nickel.

Little bit louder.

Much better.

Now the centre of the earth is extremely hot.

It's about 6,100 degree Celsius.

I know, extremely hot.

I would like you to now, add these notes about the inner core to your own diagram.

Write the under your label of the inner core.

Pause the video now, while you add your notes.

Now you've got your notes, let's move on to the next layer.

Now, the outer core surrounds the inner core.

So, the inner core is surrounded by the outer core.

This section is made of the same two metals, iron and nickel but, they are liquids rather than solids.

The outer core is slightly cooler than the inner core but it's still extremely hot.

About 4,400 degree Celsius.

I know, I'm getting hot just thinking about it.

I would like you now to pause the video and add these labels to your own diagram under the label, outer core.

Pause the video now, while you add the labels.

Well done.

Let's move on.

I've got a quick question for you.

Which two metals are the main components of earth's inner and outer core? What were those metals? Can you remember them? Shout it loud.

A little bit louder.

Iron and nickel.

Did you get that right? Give yourself a pat on the back.

Very good.

Okay so, we're now moving on to the mantle.

Now, the mantle is about 2,900 kilometres thick.

It's very thick and it's made of molten rock and this molten rock is called, magma.

My turn, your turn.

Magma.

Now, molten rock remember means, liquified by heat.

Molten liquified by heat.

Your turn? I say molten, you say, liquified by heat.

Molten.

Molten.

Liquified by heat.

Thought I was going to catch you out there.

Well done for saying molten.

Now, the average temperature of the mantle is around, 3,000 degree Celsius so it's still very very hot.

Pause the video now so you can add these notes to your diagram under the label, mantle.

Well done everyone.

Okay, the crust.

The crust is made of solid rock which is between zero and 60 kilometres thick.

The two main types of rock the crust is made of are, granite and basalt.

Your turn.

Granite and basalt.

Well done.

Now this layer, the crust, is broken into tectonic plates which move around, on top of the mantle.

Pause the video now, so you can write these notes on your own diagram.

Great.

You should now have a fully labelled diagram of the earth with all four layers and some notes underneath them.

Well done everyone.

So still thinking about what the earth is made of and to be clear about the crust, the crust is made of oceanic crust and continental crust and we're going to learn a little bit more about those.

So, oceanic crust.

My turn, your turn.

Oceanic crust.

Now, the oceanic crust is made up of the sea floor or it makes up the sea floor.

It is made of basalt and is heavier than the continental crust.

This makes it sink to the bottom of the sea.

The oceanic crust is less than 200 million years old.

I know that seems like it's very old but, it's not quite as old as the continental crust.

So, continental crust.

The continental crust forms large land masses.

It is mainly made up of granite.

It is lighter than the oceanic crust and it's more than 1,500 million years old.

It cannot be renewed or destroyed that means, it can't be made again and it can't be destroyed.

So, here we've got the labels, oceanic crust, continental crust.

Let's have a look at the definitions.

Forms land masses, mainly made of basalt, lighter than the oceanic crust, more than 1,500 years old, cannot be renewed or destroyed.

Sea floor.

Made of basalt, heavier than continental crust, less than 200 million years old.

Hmm, you might have noticed that these definitions have been mixed up.

I'd like you to put your finger on the definition that matches the oceanic crust.

Put your finger on the definition that matches the oceanic crust now.

Did you put your finger on the bottom definition? You can give yourself a tick in the air.

Well done.

Okay so now, put your finger on the definition that matches the continental crust.

Did you put your finger on the top definition? Of course you did.

Give yourself a tick in the air.

Well done.

So, let's recap on the names and locations of the seven continents.

Let's zoom in.

Where is North America? I want you to put your finger on North America.

Did you put your finger on the light green continent? Well done.

Now put your finger on South America.

Did you put your finger on the dark green continent? Well done.

Where is Europe? Put your finger on it.

Did you put your finger on the dark red continent? Well done.

Where is Africa? Put your finger on it.

Did you put your finger on the yellow continent? Well done.

Where is Antarctica? Put your finger on it.

Did you put your finger on the dark blue continent? Well done.

Where is Asia? Did you put your finger on the light red continent? Well done.

And finally, where is Australasia? Put your finger on it.

That's right.

It's the purple continent.

Sometimes, Australasia is called Oceania.

We're going to call it Australasia when we refer to it.

Now, why isn't the Arctic a continent? If you know, shout out your answer.

I can hear some of you saying the right answer.

That's right.

The Arctic isn't a continent because there's no land under the Arctic ice sheet.

Now we're familiar with the continents, we can move on.

So the earth's crust is split into plates that move across the mantle.

The plates move because the mantle underneath the plate is constantly moving in currents which therefore move the plates on top.

This means, that the plates which are made from solid rock can be moving away from each other or towards each other.

If you take a closer look on this map, you can see that there are arrows showing you the direction that the plates are moving.

So this plate, the Nazca plate, is moving in this direction whereas the Pacific plate is moving in this direction.

You can see up here that the Caribbean plate is moving in this direction.

Now, if we look closely, we can see the map shows us where the tectonic plates are in relation to each other and the continents sit on these plates.

For example, South America which is here, sits on top of the South American plate while India which is here, sits on top of the Indian plate.

I've got a question for you.

Which plate does Europe sit on? Put your finger on it and say the name of the plate.

Did you say the Eurasian plate? This plate in green? You might see that it expands across to this side of the map as well.

Another question for you.

Which plate does Antarctica lie or sit on? Put your finger on it and say the name of the plate.

Did you say the Antarctic plate? Absolutely, there it is down there at the bottom.

One more question.

Which plate is coloured in light yellow? A clue, it's a very big plate.

What's the name of the plate that's coloured in light yellow? Put your finger on it and say the name of that plate.

That's right.

It's the Pacific plate and it's very big.

It's here.

Well done everyone and you can give yourself a pat on the back.

Now, there are seven major plates.

How many major plates are there? Seven, that's right.

There are ten minor plates.

How many minor plates are there? That's right, ten.

And there is one micro plate.

How many micro plates are there? That's right, one.

Now, the micro and minor plates are just as important in shaping the earth but they are called micro and minor plates, because they are smaller than the major plates.

Here's a question.

How many major tectonic plates are there? A, one.

B, seven.

C, eight.

D, 18.

Pause the video now and choose the answer that you think is correct.

Let's check the answer.

There are seven major plates.

Pause the video now so you can tick or fix your answer.

Excellent.

Let's move on.

So now we're thinking about where do volcanoes occur and why? Now, you can see on this map, if we zoom in that the black lines on the map outline the position of the earth's tectonic plates.

So if I get my pointer, you can see that these black lines show us the position of the tectonic plates and you can even see they've been labelled in purple.

Now, the map also shows the location of active volcanoes and those are these little red dots.

I've got a question for you.

What do you notice about the location of the earth's volcanoes? You can shout out your answer.

What do you notice about the location of the earth volcanoes? That's right.

They sit on or along the plate lines.

Let's have a closer look again.

You can see, there are lots of active volcanoes along this plate line all the way along, surrounding this Pacific plate.

Now, we often call that area the Ring of Fire and that's because of course, volcanoes spew out lava which is very hot and so we can relate it to that hot fire and we call it the Ring of Fire because there's so many volcanoes that are active along that plate line.

Now where do earthquakes occur and why? Well, this map shows the location of recorded earthquakes that have occurred around the world.

What do you notice about the location of the earthquakes? That's right.

The location of the earthquakes are also along the plate lines.

Now, you can't see the plate lines on this map specifically but the earthquakes show us where the plate lines are and there are many across Europe and Asia, around and above Australasia and lots and lots along the line of North and South America.

Well done everyone for noticing that.

Now, tectonic plates are always moving but it's so slow that we do not notice it.

In fact, tectonic plates move between one and 10 centimetres every year.

Some plates are moving towards each other whilst others are moving away from each other.

The slow movement of these plates leads to violent earthquakes and volcanic eruptions and we'll learn more about that as we move on through this unit.

Here is one last task for you.

Let's zoom in.

Where are volcanoes situated? Volcanoes are situated on and around? Pause the video now so that you can answer this question using the sentence starter.

Let's check the answer.

Volcanoes are situated on and around tectonic plates.

Pause the video now so you can tick or fix your answer.

Great work everyone.

Well, that brings us to the end of today's lesson.

A really big well done on all of the fantastic learning you've achieved today.

If you're able to, please take a picture of your work and ask a parent or carer to share it with your teacher so that they can see all of the fantastic things you've learned today and if you'd like, ask your parent or carer to send a picture of your work to @OakNational on Twitter so I can see your lovely work too.

Don't forget to complete your end of lesson quiz.

Enjoy the rest of your learning for today.