# Lesson video

In progress...

Hello, my name is Mrs. Buckmire and today I'm going to be teaching you about 3-D shapes.

So make sure you've got a pen and paper and then let's begin! Okay, so the first thing I want you to do, your try this, is to sort these 3-D shapes into groups of your choice.

Now I then want you to actually describe and tell me what criteria you have used to group them.

Now, if you feel super confident, pause the video now and have a go.

If not, hold on.

I'll give you some support.

Okay so for some support, now what I've done is I've just labelled the shapes.

So ABC so just to say so it's easier to just write down what they are.

And then I just want to give you an example.

So one example might be, ooh, this group I can see a circle.

So I'd put in that group, J and F.

And in the other group, oh, I can't see any circles.

So that would be A, B, C, D, E, J, K, I, and H.

Okay? So that's one example.

You have a go now.

Okay, what groups did you come up with then? Yeah so maybe you did similar.

So, oh, in these groups, I can see a triangle.

In these groups I can see a rectangle maybe.

Anything else? Maybe you're trying to use things like faces, maybe corners, maybe edges.

Hmm, there's a couple of key words there we're about to learn about.

Good job if you did use those words.

Okay so what was one of the key words? Faces, that was one of them.

So this shape has five faces.

I'm going to show you them.

So it's got this one, which is a triangular face at the front.

It's got the same one at the back, so two, this rectangle on the side here, three, a rectangle at the bottom, four, and then this kind of diagonal leaning one, five.

So it has five faces.

So what would you say a face is in maths? Good so in maths, a face is one of the flat surfaces of a solid shape, okay? So it's flat.

Some people will say where you can draw, a face.

But it's the flat surfaces of a solid shape.

That's what I want you to remember.

So just quickly, here we have a cuboid.

But on this shape are there more or less faces? Really quickly.

What do you think? It is more! Okay, how many faces does this cuboid, this shape, have? Well done if you got six.

It is six faces.

So it's got this one at the front and the same one at the back.

And then three here, four opposite, five here, and six opposite, six faces.

So we've got five faces on this first one.

This is called a triangular prism.

We've got six faces on this next one.

This is a cuboid.

And what about this one? Looking at the definition, how many faces does this shape have? Well done if you put two.

So why is it two and not three? Some people might put three, but this is not a face.

Looking at the definition, why is it not a face? Good, it is not flat.

This is a curved surface, so it is not a face.

So we only got the one circle here and the two circle at the bottom.

So a cylinder has two faces.

So another key word was vertices.

Now I'm going to show you this one has one, two, three, four, five, six vertices.

What do you think a vertices, well a vertex, is? Good, it's a corner.

So the vertex or the vertices are the corners.

This one is a square-based pyramid.

Does it have more or less faces? What was faces again? Try and remember.

What do you think? Good, it's got the same.

Well, done for not being tricked! It's got five faces, which is the same as the other one.

Does it have more or less vertices? Well done, it has less vertices.

So this one remember the vertices are the corners.

The faces are where we can draw a face.

But vertex are the corners.

So it has one, two, three, four, five vertices, which is less than our triangular prism.

Good job.

Right last one.

We're going to look at edges.

Now, one, two, three edges I see here.

And then another three here.

So four, five, six, and then seven, eight, nine badly highlighted ones.

So it has nine edges.

How would you describe an edge? Okay, so an edge is a line segment joining two vertices.

So we know what a vertex is.

So here to here is a vertex.

And so the line joining them, that is an edge.

So we can see here we had nine edges.

So for this one.

First more or less faces? What do you think? Well done! It has more faces 'cause it has six faces and the other one only had five faces.

What about edges? What do you think? More or less? Okay, it's true.

It is more.

Now count them.

How many edges are there? Well done! So you might have done this.

I counted the front, two, three, four at the front.

So that means there's going to be four at the back.

So that's eight and then between them nine, 10, 11, 12.

So there are 12 edges.

So it is higher.

Okay, last one.

Vertices, more or less? Well done, you got more! How many? Take your time.

Vertices.

How many? Well done for remembering they're corners.

Good, this shape has eight vertices.

Okay I want you to pause the video now.

And I want you to have a go at the independent task.

It might be easier to actually press next at the bottom and look at the worksheet for this.

Okay excellent! Nice to see you all back! And hopefully the independent task was okay.

So for the first one, now we saw this shape in examples, and there should be five faces, eight edges, and five vertices.

So check those carefully.

This next one, how many faces? So there were five rectangular faces, two pentagon as faces, so actually seven faces.

And then with the edges, there's five at the front, five at the back, and then five edges connecting those vertices between the two bases, so there were 15 edges.

And vertices, did you get 10? Good! So what about this cone, hmm? Faces, how many is it? Got one, one face! It has to be a flat surface.

And edge is also just the one and vertices is up here one.

Okay, did you spot the mistakes here? Yeah? So the mistakes I got were the cuboid, the edges and faces are the wrong way round.

So these two need to be swapped around.

What about for the square-based pyramid? Ah, it has eight edges, not five! And the triangular prism? Good, it has more edges too.

It's not, it's nine, not six.

So hopefully you were able to correct all of those.

Well done.

Right my favourite activity, the explore! So we're going to compare the faces, edges, and vertices of these five shapes.

And I want you to tell me what's the same and what's different, okay? You guys can definitely do this 'cause it's quite similar to our first task.

Now, the challenge, can you think of another 3-D shape with the same number of faces as this one on the right here? Okay, so what I would do is label them first.

Let's just label them so it's easier to talk about.

Now I worked out the faces, edges, and vertices for each one so it's easier to see what's the same and what's different.

And I put it in a table.

So I wonder if you did similar 'cause I think that really helps to kind of put all your thoughts down together by organising it like this.

So what's the same? What's different? Well shape A and E both have five faces, but B, C, and D all have six.

What's different? Well for A, for the edges it's the only one with an odd number of edges.

All the others have even ones.

Maybe you came up with more different things.

Really, really well done! There's lots of things you could explore here and talk about.

Right, fantastic work today, guys! I'm really, really impressed with your efforts.

Now make sure you do have a go at that exit quiz.