Hello and welcome to today's lesson from the unit Earth, Sun and Moon.

This lesson is called The Movement of the Moon.

Hi, I'm Mrs. Waller, and by the end of the lesson today, you can use the idea of the Moon's movement to begin to explain why the Moon appears to change shape.

Yes, that's a question that I've always wanted to answer.

So let's see if we can answer this one together today.

Let's start by looking at our keywords for today's lesson.

Moon, reflect, orbit, satellite and observations.

It would be a good idea to take some time to think about which of these words you have a good idea what the definition is, and maybe which of these words you're not 100% sure about.

But don't worry because we'll be covering all of these words in the lesson today.

This lesson is in two parts.

In the first part, we'll be learning about the moving Moon, and then in the second part, we'll be learning more about the changing shape of the Moon.

We know that objects in space move in different ways.

Can you think of any ways in which objects move in space? Take a moment.

The first one that you might think of is that the Earth moves in space.

Now, the Earth rotates on its axis, and we have an image here of our spherical Earth, and we have the imaginary line going through the centre of the Earth, called the axis, and then we have our circular arrows to show the Earth rotating on its axis in an anti-clockwise direction.

Can you think of any other ways that objects in space might move? Yes, we're still thinking about the Earth at the moment.

So not only does the Earth rotate on its axis, whilst it's doing that, it also travels around or orbits the Sun.

Now that's how the Earth moves in space.

But how does the Moon move in space or does it move at all? Were you correct? Yes, the Moon moves around the Earth, and scientists use the word orbit to describe how the Moon moves.

So we have our Earth and our Moon, and again, we're using this dotted circular arrow to show how the Moon travels around or orbits the Earth, rather like how the Earth orbits the Sun.

We know that the Moon is our nearest neighbour to Earth in space, and as it's travelling around the Earth, it's known as the Earth's satellite.

Now, a satellite means to move around something.

So the Moon is the Earth's satellite, which means it moves around the Earth or it orbits the Earth in space.

Shall we compare how long it takes the Earth to orbit the Sun to how long it takes the Moon to orbit the Earth? Well, it takes the Earth approximately 365 days to travel all the way around the Sun.

Think about how enormous the Sun is.

It's gonna take rather a long time to complete one full orbit.

So does that help you to take a guess at how long does it take the Moon to orbit the Earth? So we're just going to watch a section of this animated video, just for you to get a clearer idea of how the Moon travels around or orbits the Earth.

We can see that the Moon is the Earth's natural satellite, and we know that that means that it moves around the Earth.

So the Earth is the larger object and the Moon is the smaller object.

We can see that the Moon is orbiting the Earth in an anti-clockwise direction.

In fact, at the moment, it's orbiting, it's gone behind the Earth.

So we can't just see it at the moment, but I'm sure that as it, here it is, as it continues it's orbit, we will see it again.

And if you look really carefully, you might notice that the Earth is also rotating on its axis.

Well, the answer is it takes around, not quite, but almost 28 days for the Moon to orbit the Earth once.

Now, that's nowhere near as long as 365 days is it? But we've got to consider the size of the Earth and how long it takes the Moon to travel around that, to how long it takes the Earth to travel around the enormous Sun.

Did you guess around 28 days or did you know that already? I've got even more scientific information now for you.

Are you ready? Now, this one always amazes me.

We know that the Moon travels around the Earth, so we can see our dotted line on the diagram to show where the Moon orbits the Earth.

But at the same time, the Moon is also moving in a different way.

So we have another dotted arrow on the diagram.

We can see that the Moon rotates on its axis, so like the Earth, the Moon also has an imaginary line through its centre.

So as it's orbiting the Earth, the Moon is also spinning.

Now get ready to have your mind blown even more.

As the Moon orbits the Earth and as the Moon rotates on its axis, this is all happening at the same speed.

I'm going to give you a bit more information about that.

So the Moon takes 27.

3 days to orbit the Earth, and quite often we refer to that as 28 days.

It's just that little bit easier to round it to 28 days.

But actually astronomers tell us that it takes 27.

3 days for the Moon to complete its orbit of the Earth.

Now, I wonder how long it takes the Moon to complete one rotation on its axis.

What do you think I'm going to say? Yes, that's right.

It's incredible, isn't it? The Moon takes, would you believe it, 27.

3 days to rotate once.

And you might be thinking to yourself, now, why is this information so mind blowing and what does it actually mean to us? Well, if you've figured it out yet, it's because of this.

It means that from Earth, wherever we are, we always see the same side of the Moon.

So it's the same side of the Moon that's always facing us.

Incredible, isn't it? I'm just going to stop for a moment and check your understanding of this first part of the lesson, and then we'll move on to learn about that a little bit more.

So which word describes the Moon moving around the Earth? Is it orbit, rotate or axis? And the answer is orbit.

Yes, orbit means moving around or travelling around.

Our next question, have a look at this diagram, and it shows two different orbits.

So you should be able to see orbit one and orbit two.

We've got three spheres in the diagram.

We have got A, B and C.

And my first question is, which sphere do you think represents the Moon? Do you think it's A, B or C? Yes, that's right.

It's C.

We know that C is the Moon.

It's a lot smaller than the Sun and it's much smaller than the Earth.

And the Moon is in the orbit, orbit two that would be travelling around the Earth.

Now, I'm going to stay with the same diagram, and I've already said that there's two orbits here.

Look carefully.

We have orbit one and we also have orbit two.

Take a moment just to think a bit more about what's travelling around what, what's happening in these orbits.

I would like you now to focus on orbit one, and I would like you to decide approximately how long does orbit one take? So does it take 24 hours, 28 days or 365 days? Have you decided? And the answer is 365 days.

And how do we know that? Well, we know that because orbit one is the orbit of the Earth travelling around the Sun, and that takes one year on Earth, which is approximately 365 days.

Onto your first practise tasks now.

Now we know that it's really helpful to use models to help us to understand things that we can't actually experience for ourselves.

So models are brilliant for helping us understand what's happening and what's moving in places like space.

For this task, I would like you to make a model, and I would like you to represent the Earth, the Sun and the Moon using different sized spheres.

So have a look around you, have a look wherever you are and try and find some different sized spheres, and find something that you think best represents the Earth and the Sun and the Moon.

And once you've chosen your spheres, I want you to move your model in whichever way you think is correct to show how the Moon moves in space.

So you might want to pause the video at this stage, go and collect your spheres, and have a think about your model.

Here's some ideas for you.

I've chosen a large ball, so a beach ball to represent the Sun, and a tennis ball for the Earth.

And I was trying to think of something much smaller than that, so I've chosen a marble to represent the Moon.

So once you've collected yours spheres, I want you to think about which parts of your model do you need to move? Now, remember, you're only showing at this stage how the Moon moves.

And once you're happy with your model, once you've moved some things around and you think that's the best representation, I would like you to draw a diagram to show how you moved your model.

Again, you might want to pause the video and think a little bit more about this task.

I'm going to show you some ideas now that might help you.

I'm thinking about how I'm going to use my model and what I'm going to move to show how the Moon moves.

So I'm going to move the marble around the tennis ball, and this will represent how the Moon moves around or orbits the Earth.

I know that the Moon takes around 28 days to complete one orbit of the Earth, so I'm happy now with what's moving and how that's representing the moving Moon.

And I'm going to think about how I could draw a diagram of that.

So I might want to draw three spheres to show the Sun, the Earth and the Moon, or I might just want to include the Earth and the Moon.

And how am I going to show the marble Moon travelling around the tennis ball Earth? Well, I've decided that I'm going to draw my diagram with a dotted line, and the dotted line is showing the orbit of the moon all the way around the tennis ball Earth.

Did you have similar ideas to me or did you think of something different? We're moving on now to take our understanding of the moving Moon even further.

And I would like you to sit in the middle of a room, and you're going to represent the Earth, so you need somebody to help you here.

So if somebody else could hold a ball, and that's going to represent the Moon.

Now, it would be a really good idea if you could stick something onto the ball.

So I'm going to make a little red cross out of paper, I'm going to colour it in, and I'm going to stick that onto the side of my ball.

And the reason I'm doing that is in this model, it's really important to show the part of the Moon that's facing you from the Earth.

So if you're sitting in the middle of the room and you're the Earth, and your helper, your person is standing in front of you holding the ball, and if you can make sure that you're directly facing the red cross because that's the part of the Moon that you can see right now from Earth, right? What are we going to do now? So I want you to think about how are you going to direct the person to move? What instructions are you going to give them? Because we want them to move with the ball, and we want them to model how the Moon moves.

So where are you going to tell them to go? How are you going to tell them to move? Are they going to walk anywhere? Are they going to spin or turn or do anything as they're walking? I'm giving you a few clues here now, aren't I? But if you can think about this and get some ideas together, I want you to think about how should that person move to show how the Moon moves, and why do you think this? So pause the video and take some time to get your ideas together.

Let's have a look at some possible ideas.

So I think the person with the ball should walk slowly all the way around me.

So if you're the Earth sitting on the floor and the person is going to walk slowly around you, yes, this part of the model will represent the Moon travelling around or orbiting the Earth.

And this takes around 28 days.

So I think that was probably the easier part of the model.

Now, did you remember that while the Moon is orbiting the Earth, it's doing something else at the same time? It's also spinning, it's rotating on its own axis.

So did you include this part in your model? So I think that the person should keep facing me all the way round.

They will need to rotate the ball really slowly so that I can always see the sticker on the ball.

And this part of the model represents how from Earth, we always see the same side of the Moon.

Now, that's going to be quite tricky, isn't it? So as the person is walking around you to show the moon's orbit, they also have to make sure that you can always see the red cross on the ball.

And the way that they will do that is ever so slowly they're rotating, they're spinning the ball as they're walking around.

And that's going to show both types of movement of the Moon.

It's going to show the Moon orbiting the Earth, and it's also going to show the Moon rotating on its axis.

And I hope that's going to help you to understand because of those movements, we always see the same side of the Moon, and that's the part of the Moon that for you in this model has got the red cross on it.

Have another go at this model, and explain to somebody else exactly what is happening.

I'm going to try and show you what I mean by using our model of the Moon.

And I've got little Ted here to try and help me.

So little Ted is representing the Earth, and my football with the red cross on it is representing the Moon.

And if I was just to move the Moon around little Ted, I would get to here and I would know that little Ted can no longer see the cross on the Moon.

So I'm gonna go back and start my model again.

And as I'm orbiting the Earth, I know that I've also got to very, very, very, can you see that I'm slowly rotating the ball so that when it gets to this point in the orbit, little Ted can still see the same side of the Moon.

And I'm gonna keep rotating, and I'm gonna keep, can you see me rotating the ball, rotating the ball round so that when I get to this point in the orbit, little Ted can still see the same side of the Moon.

And I would keep the ball moving around.

You're gonna see a big Moon here passing in front of you.

And as it's coming round to this side of the orbit, what I'm doing is I'm very slowly rotating the ball so that little Ted can always see the same side of the Moon.

So I'm not just moving the ball around little Ted, it is orbiting the Earth, but also remember it's rotating on its axis at the same time.

Thanks for that little Ted.

I'm going to move on now to the second part of today's lesson, and we're going to be learning about the changing shape of the Moon.

Let's start off by looking at Sofia's Moon Diary.

Now, Sofia has recorded her own observations.

She's gone outside every night for 28 nights, and she's looked up to the night sky and she's made an observation of the Moon.

And if we have a look at what Sofia has recorded, I want you to think about what has happened to the shape of the Moon.

So if we're looking at Sofia's Moon Diary, it does look like the Moon seems to change shape over 28 days.

But that's a little bit confusing, isn't it? Because we know that the Moon is always a sphere.

So at different times of the month, going back to Sofia's Moon Diary, sometimes it looks like the Moon's completely disappeared.

Sometimes it looks like the Moon is growing.

And then on a couple of nights, it looks like a lovely, great big full circle in the sky, even though it's a sphere.

We see it as a lovely, great big circle shape.

And then over the following days, it looks like it's gradually getting smaller and smaller.

And then sometimes when we look up to the sky, there's either a tiny, tiny slither of a Moon or it looks like there's no Moon at all.

And if we were to look at that with some drawings, we can go from no Moon at all to getting bigger, gradually getting bigger to a big full Moon in the sky, and then gradually getting smaller and smaller again.

So the Moon does definitely appear to change shape.

Do you think that you could explain why the Moon appears to change shape? It's a really tricky question, this one.

So take some time to give it some thought.

Let's think about this a little bit more.

So we've got the light from the Sun.

We know that the Sun is a star and it generates its own heat and light.

And we also know that light travels in straight lines.

So the light from the Sun is shining onto one side of the Earth, and we know that the side that's facing the Sun, it is daytime, and the side that's facing away from the Sun, it's nighttime.

But what's happening with the moon? So if we think about the Moon, the same thing is also happening.

The light from the Sun is shining onto one side of the moon and the other side of the Moon that's not facing the Sun is in darkness.

I'm now going to put in the orbit of the Moon because we know that the Moon travels around the Earth.

As the Moon moves around the Earth, we see different amounts of it being lit by the Sun during its orbit.

Ah, right, so it's all to do with the moving Moon.

As the Moon's moving around the Earth, we see different amounts of it being lit by the Sun.

Let's think about this a little bit more.

So from Earth here, you would observe the full side of the Moon being lit by the Sun, and that's when we would see a full Moon.

Take another minute to look really carefully at this diagram and just get it clear in your heads.

The light from the Sun, it's shining onto one side of the Earth and one side of the Moon.

And if we were on Earth right now and we were looking up at the Moon, we would see the full side of the Moon being lit by the Sun.

Yes, I've got it, have you? And that's when we would see a full Moon in the sky.

So far, we know what it looks like when we see a full Moon in the sky, but sometimes it appears that the Moon has gradually got smaller and smaller until we see no Moon at all.

And when this is happening, we actually call the Moon a new Moon.

So let me just explain to you what's happening here.

Well, there's a new Moon when the dark side of the Moon is facing us on Earth.

Remember, that's the side of the Moon that's not being lit by the Sun.

So when we look up to the night sky, there might appear to be no Moon in the sky, but we know that the Moon is always there.

It's just that the light from the Sun is shining onto the other side, the side that we don't see from Earth.

I'm going to check your understanding now of the second part of today's lesson.

Which statement below is true? The Moon's shape appears to change very quickly.

The Moon's shape appears to change many times in one night.

Or the Moon's shape appears to change slowly over one month.

Which one do you think? And the answer is C, we know that we can observe the Moon changing over around 28 days, and we can watch it changing slowly over one month.

Next question, which statement explains why the Moon appears to change shape? Is it because clouds cover parts of the Moon or the Moon orbits the Earth or the Moon moves into the shadow of the Earth? Yes, that's right.

It's B, it's actually the Moon that's travelling around the Earth, and it appears to change shape because we see different amounts of it being lit by the Sun.

Moving on to our final practise tasks now, and we are going to continue to use models.

And this time you are going to use a model to help you to understand why the Moon appears to change shape.

Now, we know that this is happening because different amounts of it are being lit by the Sun.

So let's try and use a model to help us to understand this even further.

Again, you're going to need somebody to help you with this and they're going to need a bright light, so a torch, or you could maybe use the light from a phone or a tablet.

And I want them to stand nice and still with a bright light switched on facing towards you.

And that's going to represent the light from the Sun.

You are going to represent the Earth.

And for this, it would be brilliant if you could sit down on a stool, a stool would be perfect for this, or a small table.

Or if you've got one of those chairs that swivels around a spinning chair, that would be amazing.

But if you haven't got any of those, don't worry.

We'll try our best to just use a normal type of chair.

So you are the Earth, and for this model, you're going to need a large ball.

And I quite often use a white polystyrene ball because this is a brilliant thing for modelling the Moon.

And I can take a pencil or a stick and I can push that into the ball.

And as you can see here on the image, I can hold onto that stick and that's going to represent the Moon.

So we've got the light from the Sun and we've got you as the Earth, and we know that the Moon is our closest neighbour in space.

So you've got hold of the Moon, and we're going to think about which part of the Moon can you see from Earth that's being lit by the Sun? So dim the lights, make sure that the torch is switched on, and you need to look directly at your model Moon.

Talk about how much of the Moon you can see being lit by the Sun.

Can you explain why there would be a new Moon in the sky? Now, there's lots to think about here.

So pause the video and take some time to have a go at this.

Let's think together now about how much of the Moon you can see being lit by the Sun if you're using this model.

And then also some possibilities for you to explain why there would be a new Moon in the sky at this point in the model.

So the light from the Sun, which is obviously the light coming from the torch, is shining on the side of the Moon that I cannot see from Earth.

So if we look at the picture there, we've got the Sun shining onto the other side of the Moon, and where you are on Earth, you can't see any of the side being lit.

So the side of the Moon facing me is not being lit at all by the Sun.

So to me, from Earth, it looks like there's no Moon in the sky.

And we know that this is called a new Moon.

Is that the same as what you saw or do you think you might need to go back and have another go at this part of the model? Pause the video and have another go.

So I'm going to show you some photographs of this model.

First of all, we're sitting down and we've got our polystyrene Moon on a stick.

Now, I don't know if you can notice, but if you look really closely on the door, I've got a lamp clipped onto the handle of the door, and that's a really bright light and it's representing the light from the Sun.

Now, at this moment in the model, the light is shining on the other side of the Moon.

So if we're the Earth, we would say that the Sun is shining on the side of the Moon that is facing away from us.

Therefore, from Earth, we can see the side of the Moon that is not being lit by the Sun.

And that's why from the Earth, you might look up in the sky and you might say there's no Moon tonight, but this is actually what we call a new Moon.

We're going to take this model even further now because we know that we see the Moon differently as it moves in space.

So when I said it would be great if you had a stool or a swivel chair, and you're going to just very slowly move around on your chair and then stop When you are in this position here, and this time, I want you to look directly at your model Moon.

Now, remember to hold it up.

So your model Moon needs to be a little bit higher than your head.

So what do you see now? Can you use this model to explain why has the Moon appeared to change shape? We know that it's moving in space, it's orbiting the Earth.

And you should find that it looks very different now.

What do you observe? Pause the video and have a go.

Let's think first of all about how the Moon moves in space.

During the moon's orbit from Earth, we see different amounts of it being lit by the Sun.

And this, it makes it look like the Moon is changing shape, even though we know that it's always a sphere.

So when you had to go at this model, when you were facing your Moon, which part of it did you see being lit by the Sun? Well, in this stage of the Moon's orbit, you would see the full side of the Moon being lit by the Sun.

So from you looking at it, remember that you're the Earth, it would look like there's a full Moon in the sky.

You could even keep moving around on your chair to show how the Moon orbits the Earth.

And you could look at different amounts of the Moon being lit by the Sun.

Now, when I was having a go at this model, I took some photographs at different positions as I was spinning around on my chair to show different places that the Moon might be in its orbit around the Earth.

And this was the first photograph that I took.

And as I was sitting on my chair looking up at my polystyrene Moon, I could just start to see a tiny amount of the Moon being lit by the Sun.

And this is what happens when sometimes we just see a little slither of a Moon, sometimes that's moving into what we call a crescent Moon.

And I took another photograph as I spun a little bit further around in my chair, I'd stopped, and this is where you would see from Earth a 1/2 Moon.

As I continued the orbit into the position that you've been moving to just now, I could see the full side of the Moon being lit by the Sun.

It's pretty incredible, isn't it? So here from the Earth, we would see the side of the Moon that's being lit by the Sun, and this is what we call a full Moon.

Again, pause the video and have another go at your model and take a look at how different amounts of the Moon are lit by the Sun as the Moon completes its orbit of the Earth.

And now it's time to summarise our learning from the lesson today.

We know that the Moon moves around the Earth and it takes the Moon around 28 days to orbit the Earth once.

And can you remember exactly how many days it does take? Yes, that's right.

It's 27.

3 days, but we usually refer to it as around 28 days for one orbit of the Earth.

Well done.

What else have we learned today? We know that from Earth, the same side of the Moon is always facing us.

And finally, the Moon is always a sphere, but as it orbits the Earth, we see different amounts of it being lit by the Sun.

Well done.

You've reached the end of today's lesson, and the last thing for you to do now is to have a go at the exit quiz.

There's been a lot of learning in today's lesson, so try your best, and I look forward to seeing you next time.