Hi, everyone.

My name is Mr. Ledge and I'm so excited to be learning with you today.

Today's lesson is volcanoes and their features, and that's from our unit, "Mountains and volcanoes: what, where and why?" This is gonna be a really interesting lesson with some tricky concept, but I'm here to help and we can learn together.

Let's get started, shall we? By the end of the lesson, you will be able to recognise the key features of a volcano and use the geographical vocabulary to name and explain them.

Some of the key words that we'll be using today are erupt, distribution, magma, and lava.

To erupt is to suddenly burst or break open and emit something.

Distribution is how something is spread out across a geographic area.

Magma is molten or semi molten rock underground.

Lava is molten rock that is broken through Earth's surface.

When it's still below the surface, it is known as magma.

Our learning today will be split into two parts.

The first part is, what is a volcano? And the second part is, where do volcanoes occur? So let's begin with our first section.

What is a volcano? We're gonna start today's learning with a question.

What is a volcano? We all have an image in our minds when we think of volcano.

Can you describe what you think a volcano looks like? Think about the shape, the colour, and the sound.

Pause the video now and discuss that question with your partner.

Does your volcano look like one of these potentially quite large with lava erupting from perhaps maybe a huge crater with ash cloud coming out of it? Well, you might be surprised.

A volcano is simply a crack or opening in the Earth's crust from which magma can be emitted, but doesn't always have to.

Remember, magma is molten rock from the mantle that comes to the surface.

At the surface is then called lava.

Lava can reach temperatures of up to 1,250 degrees Celsius.

Volcanoes do not have to be a specific size or shape.

They can also be above ground or on the seabed.

The volcano shown in this picture is 25 metres below the surface of the sea.

The eruption throws lava above the surface.

Okay, here we have our first check for understanding, and this is a true or false question.

All volcanoes are mountains that erupt magma.

Is that true or is that false? Pause the video now to answer that question.

Welcome back.

Yes.

The correct answer to that was false.

Well done if you got that correct.

Can you justify your answer now? So, is it because, A, some mountains do not erupt magma, or B, volcanoes are a crack or opening in Earth's crust from which magma can be emitted? Pause the video now.

Think about that question.

Welcome back.

The answer to that question was, B, volcanoes are a crack or opening in Earth's crust from which magma can be emitted.

Well done if you've got both of those questions right.

We're off to a great start.

Volcanoes come in all shapes and sizes.

Two common types of volcano are the composite volcano and the shield volcano.

Mount Fuji in Japan is a composite volcano.

Mauna Loa in Hawaii is a shield volcano.

Can you spot any differences between these two volcanoes? Pause the video now to think about that one for me.

Okay.

As you can see in this illustration picture, composite volcanoes like Mount Fuji have steep sides.

However, shield volcanoes are gently sloped volcanoes that have a large base, like a shield.

Right, we're gonna check our understanding on those volcanoes.

So true or false, composite volcanoes have gently sloped slides and a large base.

Is that true or is that false? Pause the video now to answer that question.

Welcome back.

The answer to that question was false, but can you justify your answer? Is it because, A, shield volcanoes have gently sloped sides and a large base, whereas composite volcanoes have steep sides? Or is it because, B, all volcanoes have steep sides? Pause the video now so you can justify your answer.

Welcome back.

The answer to that question was A, shield volcanoes have gently sloped sides and a large base, whereas composite volcanoes have steep sides.

Well done if you answered both of those questions.

They were tricky.

When volcanoes erupt, the magma bursts up to the surface of Earth where it becomes lava.

They can also emit dangerous gases, dust, and pieces of rock.

When the lava cools, it hardens into igneous rock on the sides of volcanoes.

This process makes volcanoes bigger and bigger.

Composite volcanoes erupt violently, but quite infrequently.

Their lava is often very thick, but moves slowly.

This means the walls of the volcano build up steeper and steeper, as the lava cools and hardens into igneous rock close to the volcano.

Shield volcanoes erupt less frequently and less violently than composite volcanoes.

The lava erupting from shield volcanoes is often quite runny, which means it runs all the way down the volcano, and that forms gently sloped sides, as you can see from the illustration there.

Okay, I've got another check for understanding here.

True or false? The steep sides of a composite volcano are determined by its lava.

Is that true or is that false? Pause the video now to answer that question.

Welcome back.

The answer to that question is true, but let's see if you can justify your answer.

Is it because, A, thick lava spreads quickly so it cools to the close to the volcano? Or B, thick lava spreads slowly, so cools close to the volcano? Pause the video now to justify your answer.

Welcome back.

The answer to that question was B, thick lava spread slowly, so cools close to the volcano.

Remember, that process makes volcanoes bigger.

Okay, we're now going to explore some of the physical features of a volcano to help us identify them and understand them more.

The mouth of a volcano is called its crater.

When volcanoes erupt, magma can erupt outta the crater, turning to lava as it runs down the side of a volcano.

Ash cloud is the gas and dust emitted from a volcano erupting.

Ash cloud is not soft and fluffy as it looks, but a hard mixture of rock, minerals, and glass.

Ash cloud can cover everything it lands on.

The main vent of a volcano is the main passage where magma travels through before it reaches Earth's surface.

Let's check our understanding here.

What is the name of the mouth of a volcano? Is it A, an ash cloud, B, a crater, or C, the main vent? Pause the video now to answer that question.

Welcome back.

The mouth of a volcano is called its crater.

Well done if you've got that question correct.

The secondary vent of a volcano is a side passage where magma can escape.

Lava, as we've learned, is molten rock or magma that has escaped from a volcano.

It is called magma when it's underneath Earth surface.

The location here underneath the main vent and underneath Earth's surface is called the magma chamber.

The magma chamber is where magma is stored before a volcano erupts.

When lava cools on the outside of a volcano, it hardens to form new layers of igneous rock.

As you know, this process makes volcanoes bigger.

Let's check our understanding again here.

What is the name of molten rock or magma that is erupted from a volcano onto Earth's surface? Is it A, a secondary vent, B, a magma chamber, or C, lava? Pause the video now to answer that question.

Welcome back.

Molten rock or magma that is erupted from a volcano onto Earth's surface is called lava.

Well done if you answered that question correctly.

You're doing great.

That brings us onto our first task for today's learning.

Can you name the physical features of volcano and write a definition for each? Pause the video now to begin that first task.

Okay, let's see if you identified the physical features of a volcano correctly.

So, here we have the ash cloud, the crater, the mouth volcano, the main vent where magma erupts from the volcano, lava, a secondary vent where magma can escape from the volcano, the magma chamber where magma is stored before the volcano erupts, and layers of rock.

Let's see if your definitions look similar and include similar snippets of information.

The crater is the mouth of volcano.

Ash cloud is the gas emitted from a volcano erupting.

The main vent of a volcano is the main passage where magma travels through before it reaches the Earth's surface.

The secondary vent of a volcano is a side passage where magma can escape.

Lava is molten rock or magma that has escaped from a volcano.

The magma chamber is the location underneath the main vent where magma is stored before a volcano erupts.

The earth is made up of layers of rock.

When lava calls on the outside of a volcano, it cools to form new layers of igneous rock.

Well done if your work included similar snippets of information.

Okay, that brings us on to the second part of our learning today.

Where do volcanoes occur? Let's find out, shall we? There are more than 1,500 active volcanoes on Earth.

Approximately 50 to 70 volcanoes erupt every year.

Volcanoes are not distributed randomly, but it takes a skilled geographer to spot the pattern.

Remember, distribution is one of our key words, and it means how something is spread out across a geographic area.

So how the volcanoes are spread out across the world.

Can you spot the map, the pattern on the map shown here? One pupil says, "There are lots of volcanoes along the lines," and they're correct.

Earth is made up of four main layers deep in the centre of Earth.

We have the inner core, then the outer core, then the mantle, and finally, the layer in which we live on, the crust.

Earth's crust is broken up into a series of enormous sections called tectonic plates, and they fit together like a jigsaw.

In fact, there are seven major plates.

The Eurasian, Pacific, Indo-Australian, Antarctic, North American, South American, and African plates.

Each move on average between 1 and 10 centimetres per year.

These tectonic plates are constantly moving as they sit on top of Earth's mantle, which is constantly melting and moving.

Okay, let's check our understanding here.

What are tectonic plates? Enormous pieces of Earth's crust that fit together like a jigsaw.

Imaginary lines on a map.

Cracks in Earth's surface.

Pause the video now to answer that question.

Welcome back.

Tectonic plates are enormous pieces of Earth's crust that fit together like a jigsaw.

Well done if you answered that question correctly.

The point where tectonic plates meet is called a tectonic plate boundary or plate boundary.

Here, you can see them on this globe highlighted by the arrows.

Okay, going back to our map, most volcanoes occur at plate boundaries, and you can see the volcanoes here marked as a red triangle on this map.

Do you notice anything else about this map in the volcanoes? Pause the video and think about that question.

The red highlighted line here is the Ring of Fire.

Well done if you notice that highlighted ring.

The Ring of Fire is a horseshoe-shaped line in a map, along plate boundaries, and that's home to 75% of the world's volcanoes.

That's over 100,000 volcanoes, and some of them are underneath the sea.

Let us check our understanding.

Can you correctly complete the sentence? The world's major volcanoes are distributed randomly, only found on land, distributed in distinct patterns along plate boundaries.

Pause the video now to answer that question.

Welcome back.

Let's see if you got that correct.

The world's major volcanoes are distributed in distinct patterns along plate boundaries.

Brilliant learning.

Well done.

Okay, we're now onto our second task for today.

Can you fill in the gaps using these words? Distributed, 75%, crust, tectonic plate, openings, Ring of Fire, plate boundaries.

Okay, let me read that out for you.

Hmm, are huge pieces of Earth's crusts which fit together like a jigsaw.

Volcanoes are not, hmm, randomly, but they occur at, hmm.

As the tectonic plates move, cracks or, hmm, form in Earth's, hmm.

This is what forms a volcano.

Hmm, of the world's volcanoes occur at the, hmm.

Pause the video now.

See if you can fill in those gaps.

Welcome back.

Does your work read like this? Tectonic plates are huge pieces of the Earth's crust which fit together like a jigsaw.

Volcanoes are not distributed randomly, but they occur at plate boundaries.

As the tectonic plates move, cracks or openings form in Earth's crust.

This is what forms a volcano.

75% of the world's volcanoes occur at the Ring of Fire.

Well done if you filled in all those gaps correctly.

That brings us towards the end of our lesson.

Let us quickly summarise what we've learned today.

We've learned that a volcano is a crack in Earth's crust from which lava is emitted.

We've learned that volcanoes are formed at the boundaries of tectonic plates.

We've learned that volcanoes take many different forms and come in lots of different shapes and sizes.

We've also learned that composite volcanoes share a common structure and they have steep sides.

Well done for all your hard work today.

You've been absolutely fantastic and I hope to see you again for some more fantastic geography.

Goodbye.