Lesson video

Hello everybody.

My name is Mrs. Johnson, I am so happy to be here today to help you with some of your maths learning.

I hope you are ready to work hard and have lots of fun.

Let's have a look at what we're going to be learning about today.

This lesson is called "Describe and name 3D shapes, prisms and pyramids." It comes from the unit shape, discuss and compare 2D and 3D shapes.

By the end of this lesson, you will be able to recognise and name pyramids and prisms and describe their properties.

You are going to be an expert on pyramids and prisms by the time we get to the end of this lesson, you will know all about them, so don't worry if you don't know anything about them yet, because I am going to help you and by the end of the lesson, you will know lots about pyramids and prisms. There are two keywords in this lesson.

I've already mentioned them a few times because they are the most important words in this lesson today.

Let's practise saying them.

My turn first and then your turn, ready? My turn, pyramid.

Your turn.

My turn, prism.

Your turn.

Well done.

These words are really important in this lesson today, so listen out for them.

There are going to be two parts to this lesson.

To begin with, you are going to learn about pyramids and then in a little while, you are going to learn about prisms. Let's start by learning about pyramids.

There are two friends who are going to help in this lesson today.

Their names are Lucas and Laura.

Listen and watch Lucas and Laura carefully because they have lots of really helpful things to show you today.

Have a look carefully at these two shapes.

What is the same about them and what is different? You've got shape A and shape B.

Lucas and Laura have had a look at these shapes.

They're going to tell you what they noticed.

I wonder if the things that they notice are going to be the same as the things that you might have noticed.

Let's have a look.

Lucas has noticed some things that are the same.

He says, they both have some triangular faces, some faces that are triangles.

They both have one vertex at the top.

They both have more than one vertex at the bottom.

All the faces on both shapes are flat.

There are no curved surfaces.

Wonder if you noticed any of those things too? Laura noticed some things that are different.

Let's have a look at what Laura noticed.

A, has only triangular faces, but B has triangular faces and a square face.

B has a square face at the bottom.

They have a different number of faces.

B has more edges and more vertices than A has.

Laura's been thinking carefully about the properties of these shapes, hasn't she? The faces, the vertices and the edges to notice some things that are different.

I wonder if you noticed any of those things too? These shapes are both pyramids.

We can have a look at some more pyramids too.

These shapes are pyramids as well.

Lots of different pyramids here.

These are all pyramids, but Laura has noticed that they have different shaped faces.

How can they all be pyramids when they don't all have the same faces? Lucas says, maybe there are properties that pyramids will always have common.

Maybe it's not the shape of the faces or the number of faces.

Maybe there is something else that pyramids always have to have.

I wonder.

Let's have a look what that might be.

A pyramid always has some triangular faces.

You can see on all of these pyramids that they have some triangular faces.

The triangular faces will all meet at a single vertex called the apex.

Here's the apex on these pyramids.

The triangular faces are meeting, aren't they, in a vertex, which is called the apex, so they all join, they all meet at a point, and that point has a special name called the apex.

A pyramid always has one apex.

A pyramid always has one face opposite the apex.

The face opposite the apex is called the base.

Here's the base on these pyramids.

It's not always the same shape, but it is always a polygon.

Remember, a polygon is a 2D shape that is made up of three or more straight sides.

So we can see here, can't we? That the base is always a polygon because it either has three sides or four sides, or six sides, or five sides, three or more sides, and they are always straight.

So the base of a pyramid is always a polygon.

Laura says, this is a pyramid because it has triangular faces that meet at an apex.

She is right, isn't she? Lucas says, this is not a pyramid because it does not have a base.

He is correct.

This shape is not a pyramid.

It looks like two pyramids that have been joined together.

Let's check if you could finish off Lucas's sentence.

This is a pyramid because.

Pause the video and have a think.

How could you complete this sentence? There are lots of things you could have said.

Let's have a look at some of the things that you might have said to complete Lucas's sentence.

You could say, this is a pyramid because it has an apex and a base.

You could say, this is a pyramid because it has some triangular faces that meet at a vertex.

Well done, if you remembered either of those points about a pyramid.

Let's see if you can think about how you could complete Laura's sentence.

This is not a pyramid because.

Hmm, pause the video and have a go.

Let's see, this time you could have said, this is not a pyramid because it has no triangular faces.

This is not a pyramid because its base is not a polygon.

It has a circle as a base.

A polygon needs to have three or more straight sides.

That's why this is not a pyramid.

Well done, if you remembered either of those.

A pyramid can be named after the shape of its base, so these are all pyramids, but they do each have their own name, which comes from the shape of their base.

On this pyramid, the base of the pyramid is a triangle.

We would call this a triangular-based pyramid.

On this pyramid, the base is a square, so we would call this a square-based pyramid.

And on this one, the base is a pentagon, so we would call this a pentagonal-based pyramid.

Let's check if you can work out the name of this pyramid.

The base of this pyramid is a, mm.

This is a mm, pyramid.

Pause the video and have a think, what could this be? Well done for thinking carefully.

Did you count the sides of the face that is the base? You should have found that it has six sides.

What do we call a shape that has six sides? That's right, it's a hexagon.

The base of this pyramid is a hexagon.

That means that this would be called a hexagonal-based pyramid.

Well done if you worked that name out.

That was a tricky question, great job.

Now it is time for you to practise naming some pyramids.

You are going to use the words in the box to help you to write the name of each 3D shape.

Look carefully at the shape of the base of each pyramid to help you work out the name.

Then you are going to have a look at these sentences and tick the sentences that are true.

A pyramid always has some triangular faces.

A pyramid has only triangular faces.

The base of a pyramid is always a square.

A pyramid can have any polygon as its base.

The apex is the vertex where the triangular faces meet.

A pyramid is named after how many faces it has.

Think really carefully about each sentence and tick the ones that are true.

Then you are going to have a go at question number three.

It's a true or false question.

All pyramids have the same number of vertices.

Do you think that is true or false? I would like you to draw or write in the box to show how you know, draw or write down your ideas to show how you know that this sentence is true or false.

Pause the video and have a go at that now, off you go.

Let's see how you got on.

First of all, you needed to name the shapes.

We should have a triangular-based pyramid, a square-based pyramid, a pentagonal-based pyramid, and a hexagonal-based pyramid.

Well done if you named those correctly.

On the second question, you needed to decide if the sentences were true or false.

A pyramid always has some triangular faces.

That is true.

A pyramid has only triangular faces is false.

It can have a face that is different shape.

The base of a pyramid is always a square.

No, we can have different shape bases, can't we? A pyramid can have any polygon as its base.

Yes, that is true.

The apex is the vertex where the triangular faces meet.

That is true.

A pyramid is named after how many faces it has.

That's not true.

A pyramid is named after the shape of its base.

That's why we can have a triangular-based pyramid or a square-based pyramid.

It comes from the name of the base.

Question three.

You need to decide if this sentence was true or false.

All pyramids have the same number of vertices.

This is what you might have drawn or you might have been thinking about.

You could have a triangular-based pyramid, that would have four vertices.

If you had a square-based pyramid, that would have five vertices.

If you had a hexagonal-based pyramid, it would have seven vertices.

These drawings show that this sentence is false.

When a pyramid has a different base, it means that the number of vertices will be different as well.

Well done if you showed that this sentence was false by talking about the number of vertices on different types of pyramids.

Now it's time for the second part of our lesson.

Now you are going to learn all about prisms. Have a look carefully at these two shapes.

What is the same about them and what is different? Lucas and Laura have been looking at these shapes.

We're going to have a look at what they have noticed.

I wonder if they are going to notice the same things that you might have spotted about these shapes.

Let's have a look.

Lucas has noticed some things that are the same.

He says, they both have some rectangular faces.

They both stand like a tower.

The towers stay the same width all the way down.

They don't get wider.

All the faces on both shapes are flat.

Lots of things that Lucas has noticed that are the same.

Did you notice any of those things too? Let's see what Laura has noticed.

Laura has noticed some things that are different.

Oh, I wonder if she's going to notice the same things that you might have spotted.

Laura says that A has some triangular faces, but B has some pentagonal faces.

She noticed that they have a different number of faces.

She noticed that A has less edges and less vertices than B has.

Laura has been thinking about the properties of these shapes again, by looking at the number of faces, vertices and edges.

These shapes are both prisms. And we can have a look at some more prisms too.

These shapes are all prisms as well.

They look quite different, don't they? Let's find out more about these prisms. All of these shapes are called prisms, but Laura says they have different shaped faces.

How can all of these be prisms when they look so different? Lucas says, maybe there are some properties that prisms will always have in common.

That means maybe there are some things that are always the same about a prism.

Let's have a look and see if Lucas is right.

Here is something that is always the same about a prism.

A prism always has two opposite faces that are identical polygons.

Let's have a look at that.

The first prism has a triangular face at the top and at the bottom.

This prism has a pentagonal face at the top and the bottom.

This prism has a hexagonal face at each end.

Each prism has two opposite faces that are identical polygons, not always the same polygon as each other, but each prism has those two opposite faces that are identical polygons.

The two opposite polygon faces are joined by rectangular faces.

We can see the rectangular faces are here, look.

It doesn't matter that these prisms have different shaped faces on the ends, they are always joined by rectangular faces.

If you cut through a prism, the face on the part that you have cut will be exactly the same as the faces at each end.

Have a look at this.

This is a triangular face.

If I cut this prism, the part that I've cut will also have a triangular face that is identical.

This one has a pentagonal face.

If I cut it here, the part that I have cut will also have an identical pentagonal face.

This one has a hexagonal face.

If I cut it here, the part that I have cut has an identical hexagonal face.

A prism is the same width all the way through from one end to the other.

It does not get wider and it does not get narrower.

It stays the same.

Lucas says, this is a prism because it has two opposite faces that are identical polygons.

He is right, isn't he? We can see this prism has hexagonal faces that are opposite identical polygons.

Laura says, this is not a prism because it gets narrower towards one end.

It doesn't stay the same all the way through.

One end is wider and one end is narrower.

This is not a prism.

Let's check if you can complete Laura's sentence.

This is not a prism because, mm.

Pause the video and have a think.

How would you complete that sentence? Let's have a look at some of the things that you could have said.

You might have said, this is not a prism because the opposite square faces are not identical.

You could say, this is not a prism because it gets narrower towards the top.

Well done if you could complete Laura's sentence and explain why this is not a prism.

A prism can be named after the shape of its two opposite identical faces.

This prism has opposite faces that are triangles, so this is called a triangular prism.

This prism has opposite identical faces that are hexagons, so this is called a hexagonal prism.

This prism has opposite identical faces that are pentagons, so we call this a pentagonal prism.

This 3D shape is a prism too.

Lucas says, I think this shape is called a cuboid.

And Laura says, I think this shape is called a rectangular prism.

What do you think? Have you seen a shape like this before? Do you think Lucas is right? Has he remembered that this shape is called a cuboid? Do you think Laura could be right? Is this a rectangular prism? Let's have a look.

This is a rectangular prism, but it is usually known as a cuboid.

Lucas and Laura are both correct.

This shape could have two different names, but it's usually known as a cuboid.

Let's check that you can name this shape.

What do you think is the correct name for this shape and how do you know? Pause the video and have a think.

This shape is a triangular prism.

Well done if you said that.

You know that it's a triangular prism because it has opposite identical faces that are triangle shapes.

They are triangular.

You might have said, if I cut through this shape, the face of the part I have cut would also be a triangle.

That's how you know that this is a prism.

You could have also said, I know this is a prism because it stays the same width all the way from one end to the other.

It does not get wider, it does not get narrower, it stays the same.

That's how we know that this is a prism.

And it's a triangular prism because the two faces at each end are triangles.

Now it's time for you to practise recognising and naming prisms. On the first question, you need to tick all the shapes that are prisms, and then I would like you to explain how do you know if it's a prism or not.

On the second question, you need to use the words in the box to help you write the name of each 3D shape.

Look carefully at the shape of the faces to help you decide on what each of these shapes is called.

You're going to pause the video and have a go at that work now, off you go.

Let's see how you have got on.

First, you needed to tick all the shapes that are prisms. These are the shapes that you needed to tick.

All of these shapes are prisms. Then you needed to explain how do you know that these are prisms? I wonder if you said something like this.

Maybe you said, I know that all the shapes I have ticked are prisms because they all have two opposite faces that are identical polygons.

Maybe you said that the identical opposite faces are joined with rectangular faces.

That's how we know that a shape is a prism.

You also could have said that they don't get wider or narrower.

A prism will stay the same all the way from one end to the other.

It won't get wider and it won't get narrower.

Well done if you were able to tick the prisms and explain how you know that they are prisms. Great work.

On the second question, you needed to use the words in the box to name these shapes.

Let's have a look and see if you have named each shape correctly.

The first one is a triangular prism.

The second one is a pentagonal prism.

On the bottom row, we have an octagonal prism and finally, a hexagonal prism.

Well done if you wrote those names correctly, you must have looked really carefully at the shape of the faces to be able to decide on the name.

Well done.

Now that you are at the end of the lesson, you have learn lots of things about pyramids and prisms. You know that a pyramid always has some triangular faces that meet at a vertex called the apex.

You know that the polygon on the base, which is the face opposite the apex, gives the pyramid its name.

You could have a triangular-based pyramid, a square-based pyramid, a pentagonal-based pyramid, maybe you could have a hexagonal-based pyramid too.

You know that a prism always has two opposite identical polygon faces.

The prism is named after the shape of these faces, so you could have a hexagonal prism, a pentagonal prism, a triangular prism.

Well done for thinking so carefully about pyramids and prisms in this lesson today.

I hope you feel like you're an expert on pyramids and prisms now that you've learned so much about them.

I hope that I will see you again soon for some more maths learning.

Bye!.