Hello, everyone.

My name is Mrs. Mehrin, and I am so excited to be learning with you today.

We are going to have such a great time learning all about different surfaces in real life and we are going to do brilliantly.

So, welcome to today's lesson from the unit, Simple Forces Including Magnets, and this lesson is called Different Surfaces in Real Life.

By the end of today's lesson, we will be able to recognise different surfaces and how friction forces can affect these.

Some of our learning is brand new, but I am here to help you and we are going to be building on our previous learning of different surfaces where we learned about planning a fair test and carrying out an investigation.

Now, sometimes learning can be a bit challenging, but that's great because it means we can really work hard together and learn lots of fabulous new things.

So, your outcome for today is to explain why some surfaces are suitable for different jobs and give examples from real life.

Let's take a look at some of the key words that are going to be coming up in today's lesson, and I'm going to be referring back to these throughout.

Friction forces, surface, grip, properties.

You may already be familiar with some of these words.

Let's find out what they mean.

So, friction forces are forces which act between the surface of objects.

The surface is the top or outside layer of something.

A grip is a firm hold or tight grasp so there is no slipping.

The properties of a material are its qualities or things it can do.

Our lesson today is split into three sections.

Let's begin with our first one, friction forces can be useful.

Now, I've got a question for you.

Have you ever tried to walk on ice? Ice is really difficult to walk on, isn't it? Because it's very smooth and a smooth surface does not create much grip with our shoes.

We need friction forces to be able to walk without slipping.

How do you think rock climbers use friction forces to grip the surface of the rock? Have a think.

Fantastic.

So, rock climbers often wear shoes with rubber soles.

An important property of this material is that it creates high friction forces with the surface of the rock.

Goalkeepers need to be able to grip onto a ball to stop goals being scored.

Their gloves are made using fabric that has properties suitable for creating high friction forces with the surface of the ball.

Can you think of other examples where friction forces are useful? Fantastic, let's find out.

So, friction forces are helpful when riding a bike.

Can you think of why that might be? That's because friction forces allow bikes and cars to go round corners.

How about when we are writing? Well done.

Friction forces allow us to hold pencils.

And the last one, how do friction forces help us when we're playing something like baseball? Wonderful, friction forces allow us to grip the bats.

Well done, some fantastic thinking there.

Now, let's see if you can work out what the missing word should be in this sentence.

Friction forces help us to (pauses) onto surfaces.

Friction forces helps us to (pauses) onto surfaces.

What do you think the missing word might be in this sentence? Fantastic, the answer is grip.

Friction forces helps us to grip onto surfaces.

Well done.

Let's do some questions now to check our understanding so far.

So, which two of these are made easier by friction forces? Is it, a, holding a cricket bat, b, sliding down a slide c, doing a handstand? Have a think.

Fantastic, the answers are a and c.

Can you explain why? Have a think.

Fantastic, well done.

So, when we're holding onto a cricket bat, we need those friction forces so it doesn't slide away.

And when we're doing a handstand, we need friction forces so that we can grip onto the ground.

So, task A, your local football team need to find the best fabric for goalkeeping gloves.

So, your gloves could be made from different fabrics.

So, here we've got some towelling, we've got some wool, and some bin bags as well.

So, I'd like you to talk about what properties a fabric used for goalkeeping gloves needs to have and think about how you can explore and test different fabrics for goalkeeping gloves.

So, the first one is talking about the properties of goalkeeping gloves.

So, Andeep says, "I think the surface of goalkeeping gloves needs to be rough and bumpy so there is greater friction force and more grip." And I'd also like you to think about how you can explore and test these fabrics.

So, Lucas says, "I will feel how easy it is to move the fabrics across each other." And Sam says, "I will slide the fabrics over a smooth surface." So, do you have any other ideas? Well done, fantastic.

So, you may be thinking that you'd like to try on the gloves and see how they feel or catch a ball to see how useful they are.

So, we're going to explore and test the fabrics for goalkeeping gloves.

So, the first thing that you're going to do is to feel the different fabrics.

Then, you're going to put on a pair of these gloves and see how easy it is to move the palms of your hands over each other.

And then, finally, I'd like you to wear the gloves and see how easy or difficult it is to pick up or catch a smooth ball.

So, you may like to pause the video here so you can have a go at these activities.

Fantastic, well done.

So, let's see what Lucas, Sam, and Andeep says because you might have found out the same things as them.

So, Lucas said, "The wool gloves felt soft and had bubbly bits." Andeep said, "The towelling gloves felt rough on my fingers." And Sam said, "The gloves made from bin bags were smooth." So, did you find out some of the same things as Lucas, Sam, and Andeep? Fantastic, well done.

Next, I asked you to move the gloves over each other.

So, let's see what Lucas and Andeep found out and whether or not you found out the same thing as them.

Lucas said, "The wool gloves could move over each other easily, but the towelling gloves took more effort." And Andeep said, "The towelling gloves kept sticking together, but when I wore the bin bag gloves or the wool gloves, it was easy to move my hands over each other." And finally, I asked you to pick up or catch a ball, and you might have found the same thing as Lucas or Andeep.

Andeep said, "It was really hard to catch the ball when I wore the bin bag gloves because they kept slipping.

They wouldn't make good goalkeeper gloves because they don't create much friction forces." And Lucas said, "The towelling gloves would make the best goalkeeper gloves because they didn't slip when I tried to pick up the ball.

They created the most friction forces with the ball." Now, we're onto section two of our learning, friction forces can be unhelpful.

So, if there is too much friction force, it is difficult for an object to move over a surface.

Let's take a look at this picture.

How easily do you think this car would drive in deep mud? Have a little think.

Fantastic, well done.

And how easily would a ball roll through this long grass? Like you to have another think.

Fantastic, well done.

Finally, I want you to think how are friction forces unhelpful in these examples? Brilliant, well done.

So, you may be thinking, well, for the car to drive through the deep mud would not be very easy at all.

And the friction forces are quite unhelpful if the car is trying to drive through because those friction forces are going to make it harder for the car to drive through the mud.

And you may be thinking it would be quite difficult for a ball to roll through the long grass, and you would be correct.

It would be really difficult for a ball to roll through the long grass because of all the friction forces, and therefore it would be quite unhelpful.

Friction forces can often cause surfaces to wear away, so let's have a look at some examples of where that's happened.

The sole of a shoe and a bicycle tyre.

I want you to have a think about how these surfaces have been worn away by friction.

You can pause the video if you like and you can make some notes or you can just have a think.

Fantastic, well done.

Well, we can see that the friction forces have worn away at the sole of the shoe and the bicycle tyre and there is hardly any grip left on either of them.

Now, I want you to have a think.

Have you ever been injured by friction forces? And how might that look? So, this is a grazed arm at the elbow.

If you fall on a rough surface like the playground, it is friction forces that wear your skin away, giving you a graze or a cut.

In engines and other machines, friction forces can wear away important parts.

So, this is the inside of a machine worn away by friction.

To make the moving parts of machines, engineers select materials with properties that reduce friction and help surfaces to move over each other more easily.

Let's have a look at these questions to check our understanding.

So, which two of these statements are true? A, friction forces can wear away surfaces, b, friction forces can make it difficult to move, and c, friction forces can make things heavier.

Have a little think.

Fantastic, the answers are a and b.

Friction forces can wear away services, and b, friction forces can make it difficult to move.

For skateboarding, friction forces can be helpful and unhelpful.

So, we're going to match the endings to the correct sentence starters.

So, our sentence starters are friction can be unhelpful for skateboarding because, and friction can be helpful for skateboarding because.

So, friction can be unhelpful for skateboarding because it slows down objects moving over a surface so the skateboard can stop, or more effort is needed to make the wheels move across the surface.

And friction can be helpful for skateboarding because it slows down objects moving over a surface so the skateboard can stop, or more effort is needed to make the wheels move across the surface.

So, you can pause the video here if you'd like, and I'd like you to match the sentence starters with the correct endings.

Fantastic, well done.

So, friction can be unhelpful for skateboarding because more effort is needed to make the wheels move across the surface.

And friction can be helpful for skateboarding because it slows down objects moving over a surface so the skateboard can stop.

Well done, you are doing fantastically.

So, Laura and Jacob are discussing which properties of a material would be best for the sole of a sports shoe.

Laura says, "It should be made of a material that creates low friction forces so you don't have to work hard to run." And Jacob says, "It should be made of a material that creates high friction forces to stop you slipping on the floor." Who do you agree with and why? Fantastic, well done.

Let's find out who was correct.

They are both correct.

For some products, like sport shoes and tyres, materials are needed that offer enough grip so you don't slip, but not too much grip that you can't move.

So, now we are on to the final part of our learning, friction forces can create heat.

Friction forces can create heat.

Sometimes this heat can be useful.

For example, friction forces between two sticks can create fire, and friction forces create the heat needed to light a match.

Sometimes heat created by friction forces can be unhelpful.

Friction forces between surfaces in engines can make them overheat and stop working.

And friction forces between moving plastic parts in machines can cause them to melt.

To prevent dangerous levels of heat in machines, engineers sometimes add oil or grease between surfaces because they can reduce friction forces.

Cyclists add oil to the gears on their bikes to reduce friction forces.

Oil and grease allow surfaces in moving machine parts to slide smoothly past each other.

So, let's have a think.

Can you work out what the missing word should be in this sentence? When you rub two sticks together, (pauses) forces can create heat and make the sticks burn.

What is our missing word in this sentence? Have a think.

Fantastic, well done.

The answer is friction.

When you rub two sticks together, friction forces can create heat and make the sticks burn.

Well done.

True or false, it is not always helpful that friction forces creates heat? Is that true or is that false? Have a think.

Fantastic, the answer is false.

It is not always helpful that friction forces create heat.

Now, let's see if we can put that into a sentence.

So, I think this because a, when friction forces heat up the moving parts in engines, it can cause overheating and damage, or b, when friction forces heat up the moving parts in engines, they work better.

Which one do you think it is? Fantastic, the answer is a, I think this because when friction forces heat up the moving parts in engines, it can cause overheating and damage.

Task C, you are going to investigate friction forces between the surfaces of your hands.

So, for your first activity, I'd like you to rub the palms of your hands together for 10 seconds.

And whilst you're doing that, I want you to describe how they feel and why do they feel like this? So, you can describe this to a partner, or to a teddy, or even to yourself.

So, I'll give you 10 seconds to do that now.

Fantastic, well done.

Now, I'd like you to put small blob of hand cream on the palm of one hand and then rub the palms of your hands together again for 10 seconds.

And I want you to think, do you observe any difference in how your hands felt with and without the hand cream? So, I'll give you another 10 seconds to do that.

Fantastic, well done.

So, I asked you to observe any difference in how your hands felt with and without the hand cream.

Now I want you to think about if there was a difference, why do you think this was? Fantastic, well done.

So, Aisha says, "After I rubbed my hands together, they felt warm because rubbing them together created friction forces between them, and this creates heat." And Sam said, "When I rubbed my hands together with the hand cream, they didn't feel as warm.

The hand cream reduced the friction forces between my hands, so less heat was created." Were your observations similar or different? Fantastic, well done.

So, let's have a look at our summary.

Friction can be a useful force.

It can help us grip so we can walk and hold onto things.

Friction can be an unhelpful force.

It can wear away surfaces and make it difficult to move.

Scientists, designers, and engineers choose materials that have suitable properties for their work or products.

And friction forces can create heat.

Thank you so much for your hard work today.

You have been absolutely brilliant.

I have loved learning about different surfaces in real life and how friction forces can affect these.