Hello, my name is Mrs. Mehrin, and I'm so excited to be learning all about shadow shapes, and we're going to be doing an investigation today.

Let's begin.

Welcome to today's lesson from the unit light and how it travels.

Your lesson outcome today is I can use the idea of light travelling in straight lines to explain shadow shape.

Now I know that learning can be a little bit challenging sometimes, but that's okay.

It just means that we are going to work really hard together, and we are going to do a fantastic job.

Now, here are your keywords for today.

I am going to be referring to these keywords throughout today's video, so you don't need to pause the video here and write them down.

However, if it does help you to, you can write them down now.

Fabulous.

Well done.

And here are the definitions for those keywords.

Again, I am going to be referring to these throughout today's video.

However, if you feel that it does help you to jot them down, you can pause the video here and do that now.

Off you go.

Fantastic.

Well done.

Now, let's begin with our learning today.

Our lesson is split into two parts.

Let's begin with the first one, which is understanding shadows.

Now, light travels in all directions from a light source, and it travels in straight lines.

When something blocks light, it cannot curve around the objects to fill the gap behind it.

So what happens instead? I'd like you to think about that answer really carefully.

I'll give you five seconds to think about your answer, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

So a shadow is formed when an object blocks light travelling from a light source, and you can show the area where a shadow will be cast by drawing a scientific diagram.

Now, light spreads and travels out in straight lines from the light source.

So we can see that being represented here in this diagram.

Now, the opaque object, which is the ball here, blocks some of that light, so a shadow is formed on the wall behind it.

So there we can see would be the shadow on the wall.

Now this opaque object is blocking the light so it will form a shadow on the wall as well.

On a scientific diagram, light rays are drawn in straight lines from the light source, touching the edges of the object, and showing the limits of the shadow on the wall.

So we can see here it's showing us how big that shadow on the wall would be.

Now, the size of the shadow changes when the distance between the light source and the object blocking the light changes.

And scientific diagrams can help us to understand this.

So if an object is close to the light source, it blocks a lot of the light and makes a large shadow.

As the object moves further away from the light source, less and less of that light is being blocked, and so therefore the shadow gets smaller.

So if you look at these two diagrams on the right hand side, we can see exactly what that means.

Now, let's do a quick check of your learning so far.

Shadows form because light, A, travelling in curved lines is blocked by an object, B, travelling in straight lines is blocked by an object, or C, travelling in zig-zag lines is blocked by an object.

So I'll give you five seconds to think about your answer.

If you need longer, you can pause the video here.

Off you go.

Fabulous.

Well done.

The answer is it travels in a straight line, so travelling in straight lines is blocked by an object, and that's why shadows form.

Now, which of these scientific diagrams correctly shows the shadow? So think about everything that you've learnt about the diagram and how it needs to be drawn.

So does A correctly show the shadow? Is it B or is it C? So I'll give you five seconds to think about your answer.

However, if you need longer, just pause the video here.

Off you go.

Fantastic, well done.

So it would be B, because if we look at this diagram here, we have the lines that are pointing in the right way.

But another thing that makes it different from the other two is the size of the shadow.

On A, the shadow is too small, and on C, it's too large, but B shows how big that shadow of the car would be.

Now, scientific diagrams, remember, can help us understand shadows.

So here is your first task for today.

It says, add light rays to these drawings to mark the position of the shadows.

So think about what we've just learnt from the beginning of the video to now, and I want you to add those light rays correctly.

Remember that this would be classed as a scientific diagram.

And I want you to mark the position of the shadows on the wall.

Okay, I'm going to give you some time now.

So I want you to pause the video here, and I want you to have a go at that activity.

Off you go.

Fabulous.

Well done.

So this is what you should have got.

Now, I want you to pause the video here again.

I want you to have a look at your diagram, and I want you to have a look at the answers here.

Did you get those correct? Are the size of the shadows as well, are those accurate as well? So just pause the video here and have a go at that.

Off you go.

Fabulous.

Well done.

So now we are onto the second part of our learning today, which is explaining shadow shape.

So, let's take a look at this question here, and it says, why are these shadows different shapes? So we have a shadow of a puppet, and the shadow of a toy cow.

So why are the shadows different shapes? Why are they not both exactly the same? So I'll give you five seconds to think about your answer.

If you need longer to observe, that's fine.

You can pause the video here and you can come back once you are ready.

Off you go.

Fabulous.

Well done.

So the shape of a shadow will depend on the shape of the object which is blocking the light.

So because light travels in straight lines, the shape of the shadow will be the same as the outline shape of the object.

So we can see that here, the shadow of the puppet and the puppet itself, the actual object of the puppet, the shadow is the same as the puppet, because it's the shape of the puppet which is blocking that light, and it's the same thing for the cow as well.

Now, these shadows are cast by the same opaque object.

So we've got a tin can, and these are the shadows that are cast by them.

But if you remember we said that different objects cause different shadows to be cast, but in this instance, the object is exactly the same.

So why are the shadows different? I want you to have a really good think about that.

I'll give you five seconds, but if you need longer, you can pause the video here.

Off you go.

Fantastic.

Well done.

So it just depends on if an object is placed at different angles in front of a light source.

So it's going to block different parts of the light.

So if we look here, when that tin can is on its side, it's going to create a circular shadow, because the circular part is the part that is blocking the torch light there.

Now, if the tin can is upright, it's going to be a rectangular shadow, because it's the rectangular side of the can which is creating that shadow there.

So the outline of the can is two different shapes when observed from the two different angles.

So the shadow it casts is going to be of a different shape as well.

Now, let's do a quick check of your learning.

It says, because light travels in straight lines, the shape of the shadow will be the same what as the outline shape of the object? Would it be A, the size, B, the shape, or C, the colour? So again, I'll give you some time now to think about your answer.

I'll give you five seconds, but if you need longer, you can pause the video here.

Off you go.

Fabulous.

Well done.

The answer is the shape.

Now it says here match each shape to the shadow that it will cast.

So we've got A, B and C, and then we've got three different shadows.

So which shadow belongs to which shape? I'd like you to take some time now to do that.

I'd like you to pause the video here, so you can give that question a go.

Off you go.

Fantastic, well done.

So, A, it would be three, B would be one, and C would be two.

And we can tell that if we have a look at the shapes on each of the letters, we can see the shape, the shadow is the same as the shape.

Now, I'd like you to choose a book, and I want you to draw a diagram to explain how it casts a shadow that is the same shape as the book.

So I want you to remember to include these things in your diagram.

I want you to include the light source, the book, the shadow, and the light rays.

Don't forget to add the arrows to the light rays as well.

When you've done that, I want you to try and change the shape of the shadow by using the same book, but by holding the book at a different angle.

And I want you to have a go at drawing this too.

So I'd like you to pause the video here, and I want you to have a go at that activity.

Off you go.

Fantastic.

Well done.

So let's have a look at this diagram here.

So your diagram may have looked similar to this.

So we've got all the light rays going in the right direction.

We can see that the light is being blocked by the book, and therefore it's creating a shadow.

Then I said that you needed to try and change the shape of the shadow by holding the book at a different angle.

So your diagram might have looked a bit like this.

And it says, when I stood the book on the floor like a tent, the shadow was more triangular and there was a gap in the middle where the light could get through.

So we can see here that there is a gap, and you can see that gap in the shadow.

Now, let's do a summary of your learning today.

It says a shadow is formed when an object blocks light travelling from a light source.

Scientific diagrams can help us to understand shadows.

The shape of a shadow depends on the shape of the object blocking the light.

And because light travels in straight lines, the shape of the shadow will be the same as the outline shape of the object.

Now, you have worked really hard today and I'm so proud of you.

Well done.

You have used your critical thinking and you've drawn some wonderful diagrams to show shadows and the shapes that they can make.

Fantastic work.

Well done.