Lesson video

Hello, geographers.

It's Mr. Robertson here and I'm really excited to be here today for another fantastic geography lesson.

We're continuing with our unit, "Rivers, what's special about them?" In our last lesson, we started to look at the way that rivers flowed and some of the landforms that can occur along their course.

We're gonna be delving into this in a bit more detail today with our lesson, "The River's Journey".

So geographers to be ready for our journey on the river, do we have our geography caps? Have we got our especially waterproof explorers' rucksacks? And of course we need our geography wellies, because rivers are wet.

By the end of this lesson, you will be able to describe changes in a river and its landforms as it flows along its course.

As always, we have some keywords today There are four keywords.

I'll say the keyword first and then you repeat it back to me.

So our first keyword is course.

Fabulous.

Our second keyword is downstream.

Amazing.

Our third keyword is tributary.

And our final keyword is landform.

Ah, that is brilliant, well done, geographers.

So let's find out what these words mean.

The course of a river is the path that it takes from its source at the start to its mouth at the end.

Downstream is the direction a river flows as it moves towards the mouth.

A tributary is a smaller river or stream that joins a bigger river.

And a landform is a natural feature created by a process such as erosion or deposition.

We're going to be thinking and learning about these keywords through the course of our lesson today.

So this lesson, "The River's Journey", is in two parts.

In the first part, we're gonna be asking the question, how does the river change from source to mouth? And in part two we're gonna be asking the question, what landforms are found along a river course? Okay, geographers, let's get ready to investigate rivers.

Let's go.

Now, you might remember this diagram from our last lesson, because we said this is a really important diagram that's gonna help us understand rivers.

Just to recap, first of all, rivers flow from their source in the hills or mountains, to their mouth where they meet the sea or lake.

You can see on the diagram the source of the river right up at the top of the valley in the mountains there.

And we can also see the mouth of the river where it's entering the sea or lake.

So we know that rivers begin at a source and they flow to their mouth.

Now, we can break a river's course into stages.

If you look carefully at the diagram, you can see there are some dashed lines.

These are going to help us understand the different stages of a river's course.

The upper course is found nearer the source.

If you remember, the source is where the river begins up in the mountains and hills.

This is the middle course of the river between the two dashed lines and the lower course is nearer the mouth.

Now, it's important that we break the stage of the course into different stages, because we're gonna find that different things are happening at different stages.

We might see different landforms and the river will behave slightly differently.

So let's investigate this in a bit more detail.

First of all, let's check our understanding.

True or false question for you here, geographers.

The upper course of the river is close to the sea.

Is that true or false? I'd like you to pause the video and have a think.

Well done, geographers.

It's false, isn't it? The upper course of the river is not close to the sea, so that's false, but why is it false? I've got two answers for you here and I would like you to choose which one makes sense.

So answer A, the upper course of the river is the surface of the water, or B, the lower course of the river is close to the sea.

Which one of those makes sense? Thinking about what we've learned about where the course of the river is.

Pause the video, have a think.

I think we're gonna get this.

Yes, it's B, isn't it, well done.

The lower course of the river is close to the sea.

The upper course of the river is close to the source of the river, isn't it? Now, rivers change a lot as they flow from the source to the mouth.

I wonder if you might think about this question.

How might the river change as it flows downstream? Maybe you could help by thinking back to last lesson where we investigated rivers and their courses, or maybe you've got some experience yourselves of rivers.

How might the river change as it flows downstream from the source in the mountains or hills, to the mouth where it enters the sea or lake? Talk to the person next to you.

Pause the video, see what ideas you come up with.

Oh, well done, geographers.

I can hear some really amazing ideas here.

Lots of different suggestions about how the river might change in terms of its shape or speed.

Izzy's been doing some thinking as well and she says, "I think it might get bigger." Hmm, I think that's a really interesting idea, Izzy.

What do you think, everyone? Do we agree with Izzy? Let's find out.

So absolutely, Izzy is right.

Well done, Izzy.

The width and depth of a river get larger as it flows downstream to the mouth.

So in other words, as the river flows downstream, it gets wider and deeper.

You can see a photograph here from close to the river's source.

Can you see what the river looks like here? And here's a photograph much closer to the mouth of the river.

You might want to talk to the person next to you.

What do you notice about those two photographs? How would you know where they were? You might have noticed that in the first photograph near the source, the river is actually very narrow, isn't it, and probably quite shallow as well.

I think if we were walking in those hills, you could probably leap across the river at that stage, couldn't you? Quite easily.

However, if we look at the river photograph closer to the source, there's no way you could leap over that river, is there? It's much, much wider and because there's a a boat on it, I suspect it's going to be quite a lot deeper as well.

So those photographs are proving what we're saying that rivers get wider and deeper as they flow downstream towards the mouth.

But why might this happen? Why do you think rivers get bigger? This is a really interesting geographical question.

So pause the video, talk to the person next to you.

See what ideas you can come up with.

Wow, what a lot of amazing ideas I'm hearing.

You really have got your geography brain switched on, haven't you? So rivers get bigger as they flow towards the mouth as more water joins from tributaries and through the rock or soil.

Did you have any ideas like that? Well done if you did.

Look at this photograph here.

If you were at the last lesson, you will have seen this photograph already.

This is a photograph of a river and you can see a tributary joining the main river.

So you can see the main river is quite wide and there's a smaller river, a tributary joining it.

Now, after the tributary has joined, can you see the river is much wider? And that's because think of all that water in the tributary flowing down, that's gonna add a lot more water to the existing river, isn't it? And so as a consequence, the river is going to become wider, because there'll be our bigger volume of water and it will start to get deeper, because there will be more erosion as the flow increases.

And so we can see that the river has increased and got wider as the tributary joins it.

So let's check our understanding from what we've learned so far.

I've got a statement for you here and I would like you to choose the correct answer.

Rivers get bigger as they flow downstream, because A, the sea has eroded the river to make it bigger, B, people have made them bigger to get more water or C, more water has joined the river from tributaries, soil and the rock.

Pause the video, have a think.

All brilliant work, geographers.

Yes, it's C, isn't it? It's the fact that more water has joined the river from tributaries joining the river and also percolating through from soil and the rock.

That's why rivers get bigger as they flow downstream.

Well done if you've got that right.

So we're going to have a look at a video now and we're going to use the video to help us think a little bit about how rivers behave at different points along their course.

When you watch the video, you'll see an image of a river and it's a river near its source.

So you can see on the diagram where the video was taken, right up in the hills near the source of the river.

As you watch the video, I'd like you to look at the speed of the river and think about this question, is the river flowing slow or fast? Watch the video, talk to the person next to you, see what ideas you can come up with.

Well, wasn't that a great video? Looking at the river, you could see it there flowing, couldn't you? And the trees behind it, which you definitely knew you were near the source of the river, 'cause they had were steep hills and trees.

So what did you think? What did you notice about the speed of the river? Well, Sophia's been doing some thinking and she noted this.

She says, "I think the river is flowing quite slowly." Did you agree with Sophia? Yeah, she was right, wasn't she? Because it was quite a small river, it wasn't very deep and it was flowing pretty slowly, wasn't it? Absolutely, so well done, Sophia and well done if you also spotted that.

Right, now we're going to have a look at a different video and this video shows a river further downstream and again on our diagram we've got an arrow showing where the video was taken.

You can see it's further downstream, so we're not right up in the source, we're towards the middle of the river course.

Again, like before, I would like you to watch the video and I'd like you to decide again, talk to your partner and work out do we think this river is flowing slow or fast? Watch the video, off you go.

(water rushing) Wow, geographers, that was a really different video, wasn't it? You can really tell we've moved down river's course, can't you? So what did you think? Well, Sophia's been doing some more thinking and she said this, "The river is flowing more quickly." Do you agree with her? Yeah, I think we do, don't we? It was much quicker, wasn't it? The river was wider and it was faster.

It looked like, you know, you wouldn't be able to cross that river, would you? So we could see couldn't we further down the course, river flowing much faster.

So just let's sum up what we've learned so far.

On average, rivers become faster as they flow downstream.

Now, this can be confusing, because there are some stretches of rivers in the upper course that could be quite fast.

So we are making a general rule here.

So if we look at our diagram again, we can see in the upper course of the river near to the source, it's flowing quite slowly, whereas further down the course, it flows faster.

Okay, let's just check our understanding so far.

So Sophia has been doing some thinking about river and she's thinking about the river in the upper course.

She says this, "The river is likely to be very big and flowing very fast." Let's look at where the arrow is pointing, close to the source of the river.

Do we agree or disagree with Sophia? Talk to your partner and have a think.

Well, what do we think? Sophia, I'm not sure you quite understood it, have you? No, it's more likely that the river is going to be very small and slow in the upper course, isn't it? Think about that video we watched where there was just a very small river and it wasn't going very fast, was it? So unfortunately, Sophia, you're not quite right there.

I wonder if you managed to spot Sophia's mistake as well.

Now, in our last lesson, we started to talk about the fact that rivers transport material.

You might remember we watched the video of the snow globe and talked about how rivers can transport material of different sizes along its course.

Now, usually the rocks in a river get smaller and rounder as a river flows downstream.

So if we look at the two photographs here, we can see the photograph at the top, we've got some really big rocks, haven't we? Quite difficult, you'd struggle to lift those up, wouldn't we? And those are found in the upper course of the river closest to the source.

In the second photograph, we've got some different stones.

Can you see that these rocks are much smaller, aren't they? They're rounder and they're smoother.

And that photograph is taken from lower down in the course.

Hmm, I wonder why that is? Why do we get bigger rocks in the upper course and smaller, rounder rocks lower in the course? Have a think about that, geographers.

Pause the video, talk to the person next to you.

Wow, what amazing thinking I can hear.

You are really using your geography brains, aren't you? Let's examine the answer to this question.

So in our last lesson, we talked about erosion, that rivers erode material and the rocks in the river get smaller and rounder when they've been eroded by the river.

So this is a photograph we saw in our last lesson and we can see some sand there which has been deposited by the river.

At this stage, we are very close to the river mouth.

The river is large and wide and so the rocks have been eroded down to small, what we call a sediment-like sand.

Can you see that sand there? Looks really beautiful, isn't it? That sand is made by lots of crushed rocks that have over time have been crushed down to make that sand.

And that's because this sand, because we're at the lowest course of the river near to the river mouth, those big rocks over time have been eroded down to leave that fine sand.

Okay, let's check our understanding of this.

As the river erodes the rocks, they become A, smaller and rounder, B, larger and rounder or C, larger and more angular.

Pause the video, have a think.

Brilliant thinking, geographers.

Yes, it's smaller and rounder, isn't it? Think about those photographs we saw, the rocks get smaller and rounder and actually by the end, by the river's mouth we might even have some sand as well or mud.

Okay, let's think a little bit about what we've learned with our first task.

Aisha, Sam and Jun have been doing some thinking about rivers and they've all made a statement about the rivers.

I'd like you to think about what each of them says in turn and decide who you think is correct and see if you can work out any of the misconceptions that the others may have.

So Aisha says, "Rivers are small near the source, but they are very fast.

Then they get bigger and slower as they flow downstream." Sam says, "Rivers are really big near the source and then they get smaller and faster as they flow downstream." And Jun says, "Rivers are really small near the source and then they get bigger and faster as they flow downstream." Okay, geographers, think carefully.

Who is correct? Who has not quite understood our learning? Let's find out shortly.

Brilliant, geographers.

Right, let's see what we think.

Aisha said, "Rivers are small near the source, but they're very fast.

They then get bigger and slower as they flow downstream." So Aisha wasn't quite right, because actually rivers are more nearer the source, but they're not as fast.

They actually speed up as they flow downstream, so Aisha, not quite right there.

Sam said, "Rivers are really big near the source and then they get smaller and faster as they flow downstream." Again Sam, not quite right.

Rivers are actually small near the source, not large, but they do get faster.

And Jun says, "Rivers are really small near the source and then they get bigger and faster as they flow downstream." Jun, you are absolutely right.

Rivers are small near the source and they get faster as they flow downstream.

So well done, Jun.

And well done if you managed to work out who wasn't really understanding it and who was.

Brilliant work, geographers.

So the second part of our lesson is going to be answering this question, where are landforms found along a river? Let's go.

So we started to talk about some landforms in our last lesson and I wonder if you can remember anything that we learned.

So I have four photographs here of different landforms that rivers can create.

I wonder how many of those you can name.

Why don't you pause the video and talk to your talk partner and see which ones you can remember.

Let's find out how well you did.

So yes, there we have an amazing waterfall.

Look at that water pouring down.

Imagine the noise and spray there.

Then we have the bends in the river called a meander.

We have an estuary where the river meets the sea and we have a floodplain, the flat areas either side of the river which flood, that's why they're called a floodplain.

And again, we have an example of a meander.

Wow, well if you manage to remember those, brilliant geographical knowledge, geographers.

Let's think about where we might find these landforms. Again, we've got our diagram of our drainage basin and as we did early on this lesson, we've split it into the upper course, middle course and lower course.

Now, river landforms are formed in different parts of the river.

Some are more likely to be found in the upper course, whereas others are found in the middle and the lower course.

I wonder if you are already beginning to think, "Hmm, I wonder where each of those landforms might be found?" So waterfalls are more likely to be found in the upper course of a river.

We've got a different photograph of a waterfall here.

You can see it, can't you? It's a much smaller waterfall, but still, if we think back to our last lesson, we can see where the river has been running over the hard rock and it's met an area of soft rock and it's eroded that away.

And this is very much a feature of the upper courses.

Let's just check our understanding.

Where are waterfalls usually located along a river course? A, upper course, B, middle course or C, lower course? Paul's the video, geographers.

Let's get those memories working.

And of course, geographers, it's the upper course, isn't it? Congratulations if you got that right.

Now meanders, which remember are the bends in the river, start appearing further downstream in the middle and lower course of the river.

You can see a photograph of an incredible meander there, can't you? Look at the way the river curves round and back on itself and then back the other way.

And you can see from the diagram that this is in the middle and the lower course and that's because at that point, the river is wider and deeper and begins to move much more.

Floodplains are found in the middle and lower course of rivers.

You can see the floodplain there, can't you, on both sides.

And again, we've labelled where you might find them.

At this point, the river is much wider and when it floods it will kind of erode away that area of land to create the floodplain.

So let's match the definition to the correct word and check we are understanding these different landforms. We've got a waterfall, a meander and a floodplain and our definitions are a bend in the river, the flat area next to a river and where water flows over a steep cliff.

Let's try and match them, geographers, and see how we do.

Brilliant matching skills, geographers.

Let's see if you were right.

So a waterfall is where water flows over a steep cliff.

A meander is a bend in the river and a floodplain is the flat area next to a river.

Did you get those right, geographers? Well done if you did.

Finally, estuaries are found at the mouth where the river meets the sea.

Here's an example of an estuary.

You can see the bridge over the two parts where the river is going out into the sea and we've got the fresh water of the estuary, of the river mixing with the salt water of the sea.

Let's just check our understanding here.

Where is the estuary of a river located? Is it A, at the source, B, in the middle course or C, at the mouth? Pause the video.

Good luck, geographers.

Congratulations, yes, it's C, at the mouth of the river.

The estuary is the point where the river flows out into the sea.

Well done if you got that correct.

So our final practise task, we're going to try and plot these landform along a river and explain what we understand about them.

I've got a table for you here and we've divided that table into three sections, the upper course, the middle course and the lower course.

What I'd like you to do, thinking about what we've learned so far, is just write a sentence to describe what the river is like at each of those places.

So remember, the upper course is close to the source of the river.

So think what's the river like there? Is it small or is it large? Is it deep? Does it flow quickly or slowly? And what kind of rock sizes would we get there? Then the middle course is it the middle section.

What's the river like there? Is it the same or has it got wider or deeper or narrower? What is the material like there, the rocks and the speed? And finally the lower course as it goes out to the mouth.

What is the river like there? So a sentence about what the river is like in terms of size, speed and rock size in each of those places in the table, please.

And as well as that, I'd like you to then think about where we might find these landforms. So we have the estuary in the top left corner, the floodplain in the top right, a waterfall in the bottom left and a meander in the bottom right.

Can you match which part of the river's course you would find them in? Right, geographers, let's get ourselves ready to do our practise task.

Wow, a lot of hard work you've done.

Ah, amazing, I can see how much you've learned about rivers today.

So I've had to go filling this in and you may well have similar answers or you may have written it slightly differently to me.

So in the upper course of the river, I've said it's going to be narrow, shallow and slow with large rocks.

In the middle course it will be larger, wider and faster with small rocks and sediment and in the lower course, it will be very wide and deep with very small sediment.

It will be faster until it hits the sea where it slows down.

So we can see I've described there what the river looks like, how deep it is and what the material is like at different points of the course.

Well done if you got those right.

And our final task was matching the landforms. So we said waterfalls are found in the upper course, meanders in the middle course, the floodplain and meander in the lower course, because the river's much wider then and the estuary in the lower course, because that's the point where the river meets the sea or lake.

Well done if you've got those correct.

So today, we've been learning all about the river's journey and we've learned these things.

We've learned that the width and depth of the river gets larger and the river gets faster as it flows downstream.

We've learned that the rocks in the river usually gets smaller as the river flows downstream.

We've learned that landforms, like waterfalls, are usually found in the upper course of a river and we've learned that landforms, like meanders and floodplains, are found in the middle and lower course of a river.

Wow, what a lot of amazing learning we've done about rivers.

I really feel like I'm getting to understand them better and I hope you do as well.

Really looking forward to seeing you in our next lesson in this unit.

Thank you.