Hello everyone.

It is lovely to be learning science with you today.

I'm Dr.

Pemberton and I'm really looking forward to working through the lesson with you, so let's get going.

Today's lesson is on pushes and pulls.

I'm sure you're familiar with a push and a pull, but I wonder what we can learn about them as scientists.

The learning outcome for today is that you can measure pushes and pulls using a force metre.

It's part of our big question, how do forces make things happen? I'm looking forward to working with you as a scientist to learn more about pushes and pulls.

Are you ready? These are the key words that we'll be using in today's lesson, force, force metre, push, pull, and newton.

Are any of them new to you? This slide shows the meaning of each of the keywords.

I'll explain these words as we come across them during the lesson, so we won't spend time going through each one now.

It's just here as a reminder and you might like to come back later to check whether you understand how to use the words when you're talking about your science.

This is our outline for the lesson today.

There are three parts to it.

We'll begin by asking what are forces.

Then, we'll ask how big is the force? And finally, we'll learn about measuring forces.

We're going to get going on the first part of our lesson now.

What are forces? Pushes and pulls our forces.

Forces can make things start moving, move faster, slow down, change direction or change shape.

Here, you can see someone pushing with their arms to make the racing wheelchair move.

In this picture, the child is pulling the sledge to make it move.

Neither the wheelchair nor the sledge would move without a force.

You cannot see forces, but you can see their effects on objects.

Sometimes, we need forces to help us slow down, to keep us safe.

Here, the cyclist is pulling the brake lever to slow down their bike.

Sometimes, we need forces to help us turn or change direction.

In this picture, the ice skater is spinning on their skates.

It's a force that allows them to turn.

Finally, in this picture, the motorcyclist is turning using forces.

Nothing can move unless a force acts on it.

Pushes move objects further away, like the person pushing away the box from them here, and pulls bring objects closer, like this person pulling the box towards themselves.

Non-contact forces occur where objects are touching each other.

Magnetic forces push these magnets away from each other because similar poles are next to each other.

We say the magnets repel each other.

Have you ever tried this? Similarly, gravity pulls the leaf down without contact.

Both magnetism and gravity on non-contact forces.

Let's check what we've learned so far by trying a couple of questions.

The first one is a missing word question with a lot of blank.

I'll say blank where there's a missing word.

Blank moves objects further away and blank brings objects closer.

Blank can change the speed, direction and blank of objects.

As you get on, there's quite a lot to think about there.

Pushes move objects further away and pulls bring object closer.

Forces can change the speed, direction, and shape of objects.

I wonder how many of those you got.

Let's try another one.

This one is a matching question.

Can you match the type of force to the image? The types of forces are a contact push, a contact pull, a non-contact push, and a non-contact pull.

Let's have a look at the images.

Starting from the left, we have two magnets with the same poles next to each other.

Then we have someone walking.

Next, we see a camera falling.

It's been dropped.

And finally, there's a child playing with a toy train on a string.

Which force goes with which picture? Okay, so the non-contact push was the magnet.

The contact push was walking.

Of course, the person's feet push off the floor to propel them forward.

Next, the non-contact pull was the camera falling.

That pull was gravity and finally the contact pull was the child playing with the toy train on a string.

Well done if you've got those.

We've got one more check in this section.

In this one, you need to match the effect of the force to the image.

The effects are changing direction, changing shape or slowing down.

And in the pictures starting from the left, we can see someone stretching sticky tack, someone catching a ball, and someone turning a corner on a bike.

Which go together? Let's see.

Stretching the sticky tack was an example of a force changing the shape of something.

Catching the ball slows it down.

And finally, the bike turning the corner is an example of forces changing the direction of a moving object.

I hope you got an okay with them.

Now, it's your turn to do some science.

In this first task, we can see Lucas and Sofia are talking about forces.

Lucas says, "All forces are either pushes or pulls." Sofia says, "Not all forces are pushes or pulls because you can also have twists." Who do you agree with and why? Pause the video to think about this, discuss it with someone else, and then make sure you explain why you agree with Lucas or why you agree with Sofia.

When you finish talking, come and rejoin me for the next part of the lesson.

Welcome back.

Who did you agree with? Lucas is correct.

This is because a twist is an action which can involve pushes and pulls at the same time, so it's a type of push and pull.

Try miming twisting a piece of fabric.

Is one of your hands pushing and one of your hands pulling? Let's move on to the second part of our lesson.

Let's move on to the second part of our lesson.

In this section, we're asking how big is the force? Forces can be big or small.

It takes a big force to push a car up a hill.

That looks hard work, pushing the car on the photo.

In contrast, it takes a small force to push a doorbell.

We measure the size of forces in newton's.

The units are named after Sir Isaac Newton.

He was the scientist who described gravity.

Big forces have high numbers of newtons.

A force of about 1 N is needed to push or pull an apple.

But a force of about 300 N is needed to push or pull a wooden chair.

You can see that we've used a capital N instead of writing the whole word, newtons.

It's time to see what you can remember with a couple of questions.

What unit are forces measured in? Is it A, newtons, B, metres, or C, grammes? That's right, it's newtons named after Sir Isaac Newton.

Now, it's time for you to do some more science.

The force required to move a small apple is about 1 N.

What can you find in your classroom that you think requires less than 1 N to move it, about 1 N to move it, or more than 1 N to move it? Make a list with three items in each category.

Have a look round, see what you can find.

I suggest you lift up a few things to feel how heavy they are and to think whether they weigh less or more than an apple.

Then, when you've got some ideas, record them in a list like this one.

There's one column on the left for less than 1 N, one in the middle for things that are about 1 N and one on the right for things that you think have more force than 1 N.

Pause the video now so you can do your science.

Then when you finish, come back here and we'll carry on with the lesson.

Well done.

How did you get on? Your list might have put something like this.

Starting on the left, in the less than 1 N category, we have a pencil, a ruler, and a plastic cup.

In the middle column, for things weighing about 1 N, we have a pair of scissors, a spellings book, and an empty drinks bottle.

And finally, on the right hand side, in the more than 1 N column, we have a dictionary, a chair, and a hole punch.

Did you have any of these items? Did you put them in the same columns as we did or did you put them in different columns? Now, we're going to move on to the third and final section today.

It's called measuring forces.

We can measure the size of a force using a force metre, which is also known as a newton metre.

Why do you think it's known as a newton metre? That's right.

The unit of force is named after Sir Isaac Newton and so is the equipment used to measure force.

Force metres look like this.

They have numbers along a marked line on the outside.

This is the scale which shows the number of newtons.

Force metres have springs inside.

You can see it at the top of the picture here.

On the bottom of the spring is a marker.

They also have a hook at the bottom.

If an object is hung on the hook at the bottom, the weight of the object falls on the spring causing the marker to move down the scale.

The position on the scale where the top of the marker stops will show the size of the pull force in newtons or N.

The further the spring is pulled, the greater the force and the higher the number of newtons.

In this photo, you can see a force metre with a mass hanging from the hook.

To find out what the force is, you need to read the number that is level with the top of the marker.

In this picture I can see that the top of this yellow marker is exactly halfway between numbers three and four on the scale.

So I know that the pulling force created by the mass is 3.

5 newtons or 3.

5 N.

Sometimes, the marker does not stop exactly level with a whole number, just like we saw in the last picture where it's exactly halfway between the two numbers.

The marker on the scale I'm about to show you is near number one in both pictures.

So the two force metres are showing similar readings, but which metre is showing the strongest force? Let's look more carefully starting with the photo on the left.

Here, the market is above number one, so the measurement is less than one.

It's actually not 0.

5 N because it's exactly halfway between zero and one.

Let's look at the other photo.

In this case, the market is below number one, which means the measurement is more than one.

It's actually 1.

2 newtons.

I worked that out because I can see that there are 10 marks on the scale between one and two newtons and I counted that the top of the marker is two marks down from the whole number.

So if the marker is above the whole number, the force is less than that number and if it's below the whole number, the force is more than the whole number.

Force metres come in different sizes.

Some are designed to measure small forces.

They have very stretchy springs that are easy to pull.

This green force metre measures up to 5 N.

Other force metres are designed to measure large forces.

These ones have very stiff springs that are hard to pull.

This force metre, the red one, measures forces up to 20 N.

Force metres can be used vertically to measure downward pulls.

As you can see in this picture, the trolley pulls the hook down.

They can also be used horizontally to measure pulls that go sideways just like you can see in this picture.

Let's check what we can remember with some questions.

Can you remember which part of the force metre is which? Add the labels to the diagram.

The names of the parts are listed here, hook, spring, screw, marker, and scale.

But there's a warning.

There is one extra word that you won't need.

How did you get on? The spring is at the top.

The marker is the bit that moves up and down on the end of the spring and the hook is at the bottom of the marker.

The numbers printed on the outside are the scale.

The extra word was screw.

Let's try another one.

What force is shown in each of these pictures? You only need to say to the nearest whole number or the nearest newton.

That was tricky.

Let's start on the left with the yellow force metre.

The top of the marker is just above halfway between five and six, so the force is 5 N.

On the green force metre, the marker is between one and two on the whole number scale, but it's much closer to one, so the force is 1 N.

And on the red force metre, the marker is between six and eight on the scale, but it's only just below six.

So the force is nearest newton is number six.

You are going to practise using a force metre now.

There are two parts to this task.

First, you're going to explore the metre.

In pairs, practise gently testing the spring.

To do so, take it in turns to do the following.

One of you hold the top of the force metre and the other one very gently pull the hook to feel how easy it is to move.

Be gentle 'cause you don't want to damage it.

Next, close your eyes and try to pull exactly 5 N of force.

Then check how close were you.

For the second part of the task, use your force metre to measure the pulling forces of the items you listed in task B.

Try to measure the force to the nearest 0.

5 N and add the measurements to your table.

You can see someone in the photo measuring the pull force of this mug.

If you have more than one size of force metre, check to make sure that you've chosen a suitable one.

So use one which goes up to only a few newtons for very light objects and a stiffer one which goes up to higher newtons for heavier objects.

Also, check with an adult before testing any item in the more than one Newton column.

This is because you can damage the spring if you hang something that's too heavy on it.

Pause the video now and go and take your measurements, then come back and we'll carry on together.

How did you get on? Did any of your results surprise you? Here are my results.

I wonder if yours were similar.

Let's start with the left hand column, the things that I thought were less than 1 N.

The pull forces of the pencil and the ruler were both less than 0.

5 N and the plastic cup was 0.

5 N.

In the middle, where I had things that I thought were about 1 N, the pulling force of the scissors was actually less than 0.

5 N.

The spellings book was 1 N and the empty drinks bottle was 1.

5 N.

And finally, in the right hand column, for items more than 1 N, the pull force of the dictionary was 6.

5 newtons.

That's definitely more.

I decided that the chair was too heavy to test and the hole punch was 4 N.

I noted that I was right about all the items that needed forces less than 1 N, and those that needed forces more than 1 N to lift them.

It was harder to estimate which things needed about 1 N.

The scissors needed much less force than I'd expected.

Well, we are coming to the end of our lesson and the end of our learning.

So let's look at a summary to remind ourselves what we've learned.

Pushes and pulls are forces.

Forces can change an objects speed, direction, and shape.

Forces can be measured using a force metre, also known as a newton metre.

A force metre works by stretching a spring.

As the downward force increases, the string stretches further.

And finally, forces are measured in newtons, named after Sir Isaac Newton, and we can mark these with a capital N.

Well, thank you for joining me in this lesson.

I've really enjoyed learning about pushes and pulls together, and I particularly enjoyed using the force metre to measure them.

Well done for your hard work and have a great day.

See you next time.