Lesson video

Hello everybody! Welcome to your science lesson on magnetism with me, Miss Roberts.

It's so lovely to see you all here for this unit and I'm really excited to have our first lesson.

You might notice some fluffy hair just at the bottom of my screen.

This is Lenny the Lion and he helps me with all of my science learning.

I like to have him by my screen so that I can tell him all of my STAR words and he can listen when I talk to my screen as well.

'Cuz there's lots of things that we need to say to our screens to help remember all of the key information and vocabulary.

So, as well as Lenny the Lion, or your favourite teddy like mine, you're also going to need a few resources.

You're going to need a pencil, or a pen, a ruler, and a notebook.

I'd like you to pause the video and go and get the resources you need now.

Off you go! Okay, I think we are ready to start.

Pause the video if you need more time to get your things ready.

In this lesson, we are going to do the following.

We're going to look at our STAR words, and our STAR words are our key vocabulary that we need to remember throughout this lesson and throughout the unit.

Then we'll look at what contact forces are.

Then we'll look at what non-contact forces are.

Then we'll do some examples, and then I've got a little task for you.

I hope you're ready for the lesson, so let's get started on our STAR words.

So when we do STAR words, we go like this.

STAR words, STAR words, STAR words! Your turn! Oh, you can do it louder than that, team.

Let's try again.

STAR words, STAR words, STAR words! Your turn! Well done! Okay, you're ready for your STAR words.

Your first STAR word today is magnet.

Can you do the actions with me? Magnet.

Your turn.

And again.

Magnet.

Your turn.

Well done.

The next word is force.

Your turn.

Force.

Your turn.

The next word is repel.

Your turn.

Repel.

Your turn.

Well done.

The next word is attract.

Your turn.

Attract.

Your turn.

Well done.

Now I'm just going to pause there because repel and attract are opposite.

Repel and attract are opposite.

Well done.

When we get to looking at magnets, you'll see the difference between repel and attract.

So don't worry if they're new words to you today.

Two more STAR words to go.

Let's get going.

Okay, this one is thrust.

Your turn.

Thrust.

Your turn.

And my action looks like this because I'm imagining I'm pushing along a toy car.

So take your toy car, and imagine you're pushing it along the tracks and you're pushing it so that it carries on going without you.

So last time.

Thrust.

Your turn.

Well done.

Our last STAR word is friction.

Can you rub your hands together and create some friction? My turn, your turn.

Friction.

Friction.

Well done.

Ooh, my hands feel a little bit warm because of the friction that I've just created between my hands.

So, let's see.

What are contact forces? I've got some examples for you.

The first example we've just looked at which is friction.

Your turn.

Friction.

Well done.

The next one is upthrust.

Can you say "upthrust"? Now upthrust is when some objects are sitting on water.

Because not all objects float.

What objects can you think of that float on water? Can you tell me another one? Well done.

I thought of a boat.

That sits on water.

And also a duck, when it's swimming, sits on the water as well.

Now, we know that gravity is always acting upon every object and forcing it to the centre of the earth, and pulling it in.

However, upthrust is a force that's acting against an object when it's on water.

And that's why objects float.

Because upthrust is pushing it upwards.

The next one is air resistance.

What can you see in that small picture on the screen? What's that person doing? Can you tell me? Well done.

They're parachuting.

And air resistance is when something's falling through the air, there is a force acting upon it in the opposite direction.

And that is air resistance.

Can you say "air resistance"? Can you say it again? "Air resistance." Your turn.

Well done.

And resistance is when you're resisting something you're trying to stop it from doing something.

So the air is trying to stop the object from falling down, so it's pushing it back up through the air.

The last example of a contact force is water resistance.

Can you say "water resistance"? And again.

"Water resistance." Your turn.

Well done.

What did we just say resistance was? It's when you're trying to stop someone or something from doing something.

Well done.

So, water resistance is very much like air resistance.

If you're travelling through water, or something's falling through water, then the resistance of the water is pushing it back.

So it's an opposite force.

And air resistance and water resistance are a bit like friction.

They're both a bit like.

friction.

Well done.

Because air resistance, in the example of the parachute, is like the person is falling through the air and it's creating friction between the person well, and the parachute, and the air.

So those two things are creating air resistance, which is a sort of friction.

And it's the same as if you're in water.

So if you're swimming in the water, you're creating a friction between your body and the water.

I wonder, what are the forces acting on you that you can see on the screen that might be acting a bit on you when you're swimming? Well done.

Upthrust is pushing you up.

Now, because we're quite heavy, we fall and we sink to the bottom.

Just like lots of heavy objects do.

So those are contact forces.

Now just before we move on, can you have a think, why are they called contact forces? What does the word "contact" mean? Can you have a think and tell your screen? Interesting.

Yeah.

When you make contact, it's when you are touching.

When you make contact, it's when you are.

touching.

So all of the examples on the screen are of touching forces.

Excuse me.

So, for instance, we talked about air resistance and water resistance.

The sort of friction between the human or the parachute and the air or the water.

The upthrust is when the water is pushing up.

And friction is when any two objects are moving against each other.

So they are all types of contact forces.

I'd like you to pause your screen and read those four examples really loud and proud to yourself.

What are those four examples of contact forces? And the next one? And what's the third one? And what's that last one? Well done.

And one more question to tell your screen: Why are they called contact forces? Can you tell your screen? Because it's when two objects are in contact with each other.

So, for instance, the parachute and the air, the human and the water, the boat and the water, and in friction it can be any two objects.

Well done, team! I'm going to give you an awesome cheer, because you've been working so hard this lesson and listening really carefully to contact forces.

So, now I have some questions for you that I'd like you to think about.

Question one: When do contact forces act? Number two: When does upthrust act? And can you name those four contact force examples? Pause the video and have a go at those questions in your notebook now.

Well done.

Pause the video if you need more time to complete that task, 'cuz I'm going to go through the answers.

You'll hear me say that a lot.

Okay.

Question one.

When two surfaces are touching each other.

Question two.

When an object is pushing down on water.

And the four contact force examples were air resistance, upthrust, water resistance, and friction.

Team, just remember, for number three, you could have had them in any order.

It doesn't matter which order they're in, as long as you manage to remember all four, which I'm sure you did.

I'd like you to give yourself a tick for each of the correct answers, and if you got them wrong, I'd like you to write on the incorrect answers in your notebook so you've remembered, and also had a chance to practise writing them out.

I would like you to give yourself a pat on the back.

You've had a really good go at that task.

So let's keep going in the lesson.

So we've looked at contact forces, so now let's look at non-contact forces.

What do you think non-contact forces are? When do you think non-contact forces happen? Can you have a think and tell your screen? Good try.

So contact forces are when things are touching.

Non-contact forces are when things are not touching.

Well done.

Let's have a look at two examples of non-contact forces.

So we've learned that contract forces only act if two objects are touching each other.

For other forces, they will act even if the two objects are not touching each other.

These forces are known as non-contact forces.

This means that each object is creating an invisible force on the other object in a way that we can't see, but we can measure.

That's interesting, isn't it? So non-contact forces are invisible.

Non-contact forces are.

Invisible.

Well done.

Lenny the Lion here thinks, "What on earth are you doing? "Full of silly actions like that." But I really like doing actions to help me, 'cuz it makes it sticky in my mind.

So, gravitational force is our first example.

That's quite a long word, isn't it? Can you say "gravitational force"? How many syllables has "gravitational force" got? Let's find them.

I like to find them on my elbow.

Gra-vi-ta-tio-nal.

Five syllables.

Gra-vi-ta-tio-nal.

Can you say it with me? Gra-vi-ta-tio-nal.

Can you find them on your elbow as well, those syllables? Go on, put your arm out, and then take your other hand, and count them.

Gra-vi-ta-tio-nal.

Well done! You've done that really well.

So let me now tell you what on earth gravitational force actually is.

So sometimes gravitational force is called weight.

It's sometimes called.

Weight.

Well done.

And not "wait" like "I'm waiting for the bus to arrive." Weight, as in how heavy something is.

But it's not really how heavy something is, 'cuz that's its mass.

Weight is when it's being pulled to the ground.

It pulls everything downwards towards the ground on every planet.

So on the earth, like I've said before, everything is being pulled towards the ground.

That's why I'm sat in my seat right now, rather than floating around in the air.

That's why Lenny the Lion here can sit nicely on my hand like this.

He's not floating up in the air, because he's being pulled to the ground.

The other force is the magnetic force.

That's another example of a non-contact force.

Non-contact forces are.

What's the action for this? What does this mean? Invisible.

Well done.

Now, magnetic forces, we're going to talk about a little bit more.

So let me show you the next screen.

Magnetic forces can attract or repel.

Those are those words again.

So what's the two things that magnetic forces can do? They can attract or repel.

When two objects pull each other together, they attract.

When two objects push apart from each other, they repel.

So let's do the actions.

I want you to listen, have your hands ready.

I'm going to describe either attract or repel, and I want you to do the action to show me which one I'm describing.

When two objects pull together.

Well done.

And now say which one that is.

Attract.

Well done.

When two objects push each other away, they.

Well done.

And what's the word? Repel.

Well done.

So those are examples of the two ways that magnetic forces act upon objects.

There is another force we also need to consider which is thrust.

Remember our STAR word action? Thrust.

Can you have a go again? Thrust.

Well done.

And you can see the picture on the screen is of an older sister pushing her brother on a little toy car, because she's exerting thrust upon the toy car, so he moves forward.

So have a listen.

Thrust is a force created by a personal machine that pushes an object forward.

What is thrust? It's when you push something forward.

For example, the engine on a car pushes a car forwards.

Or, a person pushing a toy car uses thrust.

Usually, there must be contact for this force to act, but it's not always easy to see where the contact is taking place.

So we still consider it as a force when you're pushing something.

Well done.

Okay, let's see how well you were listening to your non-contact forces.

I've got some questions for you.

Question one.

Name two examples of non-contact forces.

Question two.

What words do we use for each of the following? A.

What's that word beginning with "A"? It's when they pull together.

And R.

What's that word beginning with "R"? It's when they push away from each other.

And question three.

How is thrust force created.

I've given you a clue there.

Pause the video and write the answers to this down in your notebook.

Or, if you want to, you can just tell your screen.

Then I'm going to go through the answers and make sure you're ready.

Okay, pause the video if you need more time, 'cuz I'm going to go through the answers.

The two examples of non-contact forces were gravitational force and magnetic force.

Give yourself a tick if you got those two correct.

If you couldn't remember one of them , that's okay, you can write it out now in your book.

The two words we use are attract and repel.

Give yourself a tick for each of those, and I'm sure you all remembered those.

Can you just double check for me that you've got the right spelling? Pause the video and check your spelling for the words "attract" and "repel" now, and change it if you got it incorrect.

Well done.

Spelling's really important in science, just like in all subjects where we have to write things down.

So let's make sure we're doing our absolute best to do our best spelling as well.

And question three.

A thrust force is created when an object is pushed forward.

Well done.

I've got another quick question for you.

On the screen where I talked about thrust, we said that it could be created by a human, or something else.

What was that something else? Can you remember? Hmm.

Well done.

It was a machine.

So machines can also exert thrust upon an object.

Okay, so here's the table I'd like you to draw.

On the left column are all the different types of force.

And then I'd like you to decide if it's contact or non-contact.

And then I'd like you to draw a quick sketch of the demonstration that I'm going to give you.

So pause the video and draw this table down in your books now.

I'd like you to use a ruler, and I'd like your table to have lines all the way around the edge, so that it's complete.

Use ruler to make sure your lines are straight.

Okay, pause the video and have a go now.

Okay.

The first example I'm going to show you is weight.

I'd like you to decide if this is a contact or a non-contact force.

What I'm going to do to show you this is I'm going to turn around my visualizer, so that you can see my examples.

So here we go.

Let's make it bigger so that you can see.

So what I've got is I've got Lenny the Lion and I'm going to drop him from above.

Let's do that one more time.

Okay.

So weight, is that contact or non-contact? What do you think? I'd like you to fill that in in your table now, and draw a quick sketch of some object.

You could draw Lenny the Lion if you want to, falling down.

Okay.

The next one is air resistance.

For this one, I've got a thin piece of paper.

I've actually got a twenty Euro note, because these are nice and light, and they fall quite nicely.

So, in fact, I'm going to make my screen bigger so that you can see it.

So, here we go.

I'm going to drop it.

And you can see it doesn't fall as quickly as Lenny did.

So, how is the force air resistance acting upon that piece of paper? The next one I've got is friction.

So I'm going to do friction now.

So make sure, in your table, you're deciding if this is contact or non-contact.

For this one, I'm going to rub my hands together.

So the friction is occurring between the surfaces that are touching, which in this case are my hands.

So, I'd like you to draw that in your table now.

Team, if you feel like I'm going too quickly, don't worry, you just need to pause the video, and have a go, and then restart when you are done.

So don't feel that you need to rush through.

The next example of a force I've got for you is magnetic force.

So here I've got two magnets.

And what I'm going to show you is I'm going to put one of them in the middle of the desk, and I'm not going to touch it.

With the other one, I'm going to go closer to it.

And you can see that then it's attracted.

Now, what I'm going to do is I'm going to leave the bar magnet here, but I'm going to use the other side of the magnet to move towards it.

So this time I'm using the blue, or the south pole.

Watch what this magnet does.

Interesting.

And actually, if I do this on the side of it, have a look at what happens.

Ooh.

Was I touching that? I wonder, does that give you a clue? Is that a contact or a non-contact force? Okay.

My next example is upthrust.

So, for this one, I've got some water.

And what I'm going to do with the water is I'm going to put-- I'm going to actually show you two objects.

I'm going to show you a piece of foil that I've got.

Now I've folded it up just so that it fits inside my cup here.

So I'm going to place the foil on the water, and let's see how upthrust acts upon the foil.

What's happening to the foil? It's floating, isn't it? Because upthrust on the water is pushing it back up against the foil that's being pulled towards the ground by gravity.

The other example of upthrust, so I don't mind which one you draw, is I've got a leaf here.

I've actually got a leaf from a basil plant.

So this, if I drop it on the water, and then I let go, you can see that upthrust is acting on the leaf, because it's not sinking.

It's being pushed back up by upthrust.

Is that contact or non-contact force, team? Complete your table, off you go.

Okay.

So, for water resistance, what I've got is I've got my cup again, and I've got a key, and what I'm going to do is I'm going to drop the key into the water, and you can have a think about what force is acting upon the key, and how water resistance affects it moving through the water.

That was quite quick, wasn't it, team? But as it fell through the water, it was slowed by water resistance.

What is that force? Is it contact or non-contact? Have a think.

Okay.

And my last force that I'm going to show you is thrust.

And for this one, what I've got is a fidget spinner.

Now, a fidget spinner, if it's just sat by itself, it will be absolutely still.

But what I can do is I can exert thrust against it and it will spin.

Gradually it will slow down, and eventually it will stop.

But the force thrust is a human acting upon it to move it.

So let's have one more look.

And that is an example of thrust.

But is that contact or non-contact? Have a think.

Okay.

Let's turn this back around again, because I'm going to show you your task.

So.

Okay.

Let's have a look at what I'd like you to do for your task.

Here is another table.

You've got some examples of contact and non-contact forces again, and I'd like you to sort these forces into the correct column.

So gravitational force, friction, magnetic force, upthrust, and air resistance.

Which ones are contact, and which ones are non-contact? Pause the video and have a go at your task now.

Well done.

Pause the video if you need more time, because I'm going to go through the answers.

Well done.

So the contact forces that you've seen examples of, and now have in your table are friction, upthrust, and air resistance.

Your non-contact forces were gravitational force, and magnetic force.

What I'd like you to do here, team, is I'd like you to go back to the table that you drew when I was giving you the examples.

And I'd like you to change whether they were contact or non-contact, using the information just here.

Okay.

So to finish off, I've got a think question.

And your think question for today is as follows: I've mentioned this very briefly at the start of the lesson, so let's see what you can remember.

Your clue here is that there's not just one force acting upon a swimmer when they're swimming through water.

Which ones can you think-- you can name? And then in next lesson, we'll go through this think question together, and see what you thought.

I'd also like you to have a go at asking somebody and speaking about it using what you now know about forces.

So you might ask your grown-up at home, "What do you think? Which forces are acting upon a person who is swimming?" You might ask your friend.

Whoever it is, I'd like you to have a conversation about science with somebody using this question.

And in next lesson, we'll go through it together.

Well done, everyone.

You've done such a good job today.

I am really, really impressed.

I'm going to give you a rainbow cheer, which goes like this.

Because you've worked so hard today.

Lenny the Lion and I are so impressed, and we'll be here next lesson, ready to go through your second lesson on magnetism in this unit.

Have a lovely day, everybody, and we'll see you next lesson! Bye!.