Lesson video

- Hi everyone, my name is Miss Dhillon.

And last lesson we were looking at rivers around the world.

Can you remind me what is the longest river in Europe called? Take second to think.

Good, you should have said the Volga River.

Well done, really good recall.

And in today's lesson, we are going to be looking at the following question.

How do rivers shape the land? But first let's look at the structure of our lesson today and what it's going to look like.

We will start by going through the Star Words.

Then we will be looking at the following.

We will be looking at how rivers erode the land.

Then we will be looking at how sediment is transported once it has been eroded.

We will then look to understand river processes in more depth before finally looking to enable these river processes unto an image of a river to apply our learning.

But first, you will need to make sure you need to have a piece of paper, a pen, and your brain ready to go so that you're ready to do lots of new learning in today's lesson.

On the screen, you can see the Star Words for today's lesson.

I will be explaining these Star Words in more detail throughout the lesson, but first let's say them out loud using my turn and your turn.

Erosion, attrition, hydraulic action, abrasion, solution, transportation, suspension, traction, solution, saltation.

Wow, there are so many new words to be learned in today's lesson but don't worry we will go through them as we go through the lesson.

Let's start by looking at the process of erosion.

Rivers wherever way the land, as they flow over and through it.

This process is called erosion my turn, your turn erosion, good job.

Erosion is when something wears away or breaks down.

On the screen, you can see an example of erosion.

Erosion happens in many different ways and we will be looking at how rivers use attrition, hydraulic action, solution, and abrasion to erode the lands.

Rivers erode the land in four main ways.

These are, my turn, your turn attrition, abrasion solution, hydraulic action, good job team.

We are now going to look through each one of these.

First, let's start off with attrition.

Rivers can erode the land by process of attrition.

This is when rocks collides and break up.

A good way to think of this is the example of crashing.

When a car crashes into another, parts of the car will break away as you can see in the image.

The same thing happens with rocks when they collide.

When rocks collide, they can break up.

Rivers can also erode the land through abrasion.

This is when rocks wear away each other and the river beds or the banks.

The river beds is the bottom of the river and the banks are the sides of the river.

This is quite similar to sandpapering.

It sandpaper has a really rough texture and it is used to wear down materials on a surface.

This is quite similar to abrasion where the rocks like sandpaper wear down each other the river beds which is the bottom of the river and the banks of the river which are the sides of the river.

Is now time to do your independent work.

Pause the video now to complete this true or false task.

On the screen, you can now see the answers.

Did you notice both statements were false? Well done if you did.

The reason A is false, is because when rocks collide they break up they don't stay together.

And for B, during abrasion, rocks not only just wear away each other they also wear away the river bed and the banks of the river so that is why that statement was also false.

Now, we're going to look at another way that the rivers erode the land and this is through a solution.

This is when acids in the water dissolve the rock.

We can see this as a chemical reaction as dissolving is a chemical process.

And on the screen, you can see an example of marble that has dissolved.

Finally, another way the river can erode the land is through hydraulic action.

That's quite challenging words so let's repeat that my turn, your turn hydraulic action, good job.

This is when the force of the water breaks down the riverbeds and the banks.

We can remember this as a water power.

You can see that in the image, I've picked an image to show you that it's a water power.

And we can remember that the water is powerful to break down the riverbeds and the banks.

I would now like you to pause a video to complete this task, fill in the missing gaps, using the words at the bottom of the white box to help you fill in those gaps.

You can now see the answers on the screen.

Did you manage to put the keywords in the correct place? Well done if you did.

And if you need to double check your answers, I'm gonna give you a few more seconds to look at the answers.

Well done everyone, I know you're trying really hard to learn the meanings of these keywords.

So really well done and keep up the good work.

We are now going to move on to transportation.

Once the land has eroded or has been worn away, the sediment is then transported along the river in different ways.

Sediment can consist of rocks and minerals as well as the remains of plants and animals.

Depending on how large the material is and how much energy the water has, material will be transported either through suspension, traction, solution or saltation.

And we are now going to learn about these in more depth.

You can see these full examples on the screen.

Rivers transport sediment, and that they have eroded in four different ways: traction, saltation, suspension and solution.

We are now going to go through these.

Rivers can transport sediment through traction.

This is where large rocks are rolled along the riverbed.

This is like a tractor wheel, why do you think that is? Okay, you might say it because the wheels go round and they roll as well.

So that's why it reminds us of tractor wheels that because the large rocks are rolling along the riverbed.

So that's what we call traction.

Rivers can transport sediment through saltation, where smaller pebbles are bouncing along the river bed.

This is the same as jumping beans.

Now, the reason it reminds me of jumping beans is because when you apply a little bit of heat to jumping beans, they start to jump and that's why they're called jumping beans.

This helps me remember saltation, which is where small pebbles bounce along the river beds.

Pause the video now, to complete the task on the screen.

Did you realise that one of the statements were false? Thumbs up if you did, well done.

In saltation, it's smaller pebbles that bounce along the river bed, not large rocks.

Okay, they are very big so they won't be able to bounce but small pebbles will be able to bounce along the riverbed so well done, if you notice that.

Rivers can transport sediment through suspension, this is when small sediment is carried along with the flow of the river.

Now, this reminds me of a hoverboard.

Have you ever tried a hoverboard? I know I have and I nearly felt so I don't think I'm that confident but maybe if I practise, I might become really good at being on the hoverboard.

But for now, the reason I chose a hoverboard is because on a hoverboard it carries you a long the road.

Once you've got your balance, it carries you along the road.

And this is very similar in the river because the small sediment is just carried along with the flow of the river.

Finally, the final way that rivers transport sediment is through solution.

This is when small sediment is dissolved into the water and it becomes invisible which means you can't really see it.

So this is why we liken it to invisible material.

Pause the video now to complete the task on the screen.

You can now see the answers on the screen, take a few moments to check your answers.

How did you do? Well done if you matched most, if not all of them correctly.

Rivers erode, transport and deposits which means drop-off material all along the length and whether they are eroding, transporting, or depositing depends on many factors, such as the river speed or velocity or the river depth, how deep the river is.

What does deposit mean, can you remember? Good, deposit means to drop-off.

When a river is travelling very fast, it has more energy so it can do more erosion.

This is also when rivers are able to transport the most amount of sediments because they have the most amount of energy and they can move along really quickly.

Rivers will deposit or drop-off material when they are moving the slowest, because this is when they have the least amount of energy to carry the sediments.

On the other hand, rivers will deposit or drop-off material when they are moving the slowest, because this is when they have the least amount of energy to carry the sediments.

Rivers will lose that energy when they stopped slow down, they will also lose their energy when the sediment they're carrying or the material that they're carrying is really, really heavy and really big.

They will want to let it go because they don't have the energy to carry it forward.

So just to recap, rivers lose energy when they slow down, which is the opposite of gaining energy when they move fast.

And rivers also lose energy when they're carrying sediment that is very heavy or really large.

On a river bend, the water moves faster on the outside of the bend.

This is where the water will be the deepest, because most erosion has taken place there.

The water moves more slowly on the inside of the bend.

So this is where the deposition or the dropping of materials takes place.

The deposition also makes the river more shallow because more materials are being dropped off and that's why it's not as deep as wherever erosion is happening.

This therefore takes away even more of the rivers energy.

Pause the video now to complete the task.

You need to the labels on the left-hand side to label the diagram.

You might want to use your pencil to draw the river before you label the diagram.

On the screen, you can see the answers.

Did you label your diagram like this as well? Well done, and if you have any quick fixes, you can fix the labels that weren't quite right just now.

Okay, team that is now the end of the lesson.

And I really hope you enjoyed today's lesson just as much as I did and learnt lots of new facts about how rivers shape the land.

Next lesson, we will be learning about what landforms rivers can create.

For now, if you would like to share any of the work with Oak National, please feel free to ask your parents or carers to share your work on Instagram, Facebook or Twitter, tagging @OakNational and #learnwithOak.

Bye everyone.