Lesson video

Hi everyone, I'm Miss Mitchell.

Today in maths, we're going to be sorting and describing 2-D shapes.

So if you can, find a quiet place ready to do some maths.

In today's lesson, we will be describing 2-D shapes.

You will then complete a talk task, an independent task, and then a quiz.

For today's lesson you will need a pencil and some paper.

Pause this video now to get this if you have not got it already.

I have hidden a shape behind this grey screen, but I'm going to give you a couple of clues to see if you can guess what it is.

The hidden shape has more than three sides.

The hidden shape has more than three sides.

My second clue.

It has four vertices.

It has four vertices.

What might the shape be? So we know for a fact that it's got four vertices, and we know it's got more than three sides.

Now, what we should realise is that if it's got four vertices, that it must also have four sides.

So we know that we are looking for a quadrilateral.

Do you think you can guess what my shape is yet, or do you need a couple more clues? Okay.

My next clue.

What can you see? You can see a little bit of my shape, but what can you see? I can see two vertices.

And at these vertices, I can see two right angles.

So that means this is 90 degrees, and this is 90 degrees.

So we are looking for a quadrilateral, a four-sided shape that has at least two right angles.

Can you please guess what my shape could be? That's right.

My shape is a square.

These four sides are all the same length.

Could my shape have been something else? Could it have been something different? Yes, that's right.

It could also have been a rectangle.

So if you guessed square or rectangle, well done.

I have got another shape hidden behind my grey screen.

Do you think you can guess what it is or do you need some clues? Okay, clue number one.

It has fewer than seven sides, but more than four sides.

So it has less than seven, but more than four.

What could my shape be? Could you tell me? Okay, good guessing.

What if I show you this picture? And I can tell you a couple more clues to help you.

There are two right angles that you can't see.

So in this grey section here on the shape, there are two right angles.

I can also tell you your last clue, is that there is one line of symmetry.

One line of symmetry.

So if I used a mirror, it would only be identical one way.

Do you think you know what my shape is? Can you guess? Why do you think it's that shape, could you tell me? And here is my shape.

Now, it looks a little bit like a house, doesn't it? But it's actually a five-sided shape.

So that means it is a.

Fantastic, pentagon.

But what do you notice about this pentagon than other pentagons we have seen? That's right, the angles and sides look a little bit different.

In fact, they are all different lengths, or I should say they're not all the same length, which means it is an irregular pentagon.

Can you say irregular pentagon? Well done.

Now a regular pentagon is when all the sides are the same length and all the angles are the same size.

But in this pentagon, we know the angles aren't all the same size because this is a right angle, and this is a right angle, but this, this and this, they are not right angles, which is why it is irregular.

Can you say irregular? Here is your talk task.

Now, what I would like you to do, I would like you to pause the screen, and I would like you to tell me what shape you can see, and what shape you can predict.

So, for example, I might say, "I can see that this shape here is a circle.

"I know this because it has one side." Now let's take a look at this shape over here.

Now, looking at it, I think it could be a pentagon, but I don't know for sure.

But I think it's a pentagon because I can see at least one, two, three, four sides.

And it is most likely that there'll be a fifth side behind here.

So although I'm not certain, an educated guess would be that this shape here is a pentagon.

Can you please pause the video and have a go yourself? Okay, now, can you please pause the video now and look at these shapes, and what do they have in common? Do any of these shapes have anything in common? So do they have anything that is the same? So for example, I can see that this shape, this shape, and this shape here, the yellow, light blue and red all are common because they all have four sides.

What did you think of? Now, can you have a look at these shapes and see what is different about them? It might be their angles are different.

It might be the number of right angles are different.

It might be they have different numbers of vertices, or sides, or even lines of symmetry.

So pause the video now, look at these shapes and decide what is different about them.

Now this here, I can see two circles that are overlapping.

Now this is called a Venn diagram.

Can you say Venn diagram? Venn diagram.

Now, what we are going to do, we're going to sort shapes according to different criteria.

So that just means we're going to sort shapes in different ways.

So we're going to look for things that are the same about them.

So can you have a think about what two headings could go above here? Here are my examples.

So my heading for this circle over here are shapes that have four or more sides, four plus sides, which means four or more sides.

Now this over here, this circle is for shapes that have two or more right angles.

Can you remind me what a right angle is? That's right, it's an angle that is 90 degrees, usually found in squares and rectangles.

So these are my two headings.

Now, all the shapes that have four plus sides are going to go in this circle, and all the shapes that have two or more right angles are going to go in this circle, but what's going to go in the middle? Can you take a guess for me? That's right, it goes in the middle if it is both, if it has four or more sides, and if it's got two or more right angles.

So for those shapes that you could put in both circles, go in the middle section.

Are there any shapes that you can see that have four or more sides and have two or more right angles? That's right.

The square has one, two, three, four sides.

And it has at least two rectangle, sorry, it has at least two right angles.

One, two, three, four, in fact, it's got four right angles.

Just like the rectangle.

It has one, two, three, four sides.

And it has at least two or more rectangles, sorry, right angles, I don't know why I keep saying rectangles.

It is right angles.

One, two, three, four right angles.

Fantastic.

Now, are there any shapes that you could put into just this circle? So they are shapes that have four or more sides, but have zero or one right angle.

Are there any shapes that fit in this circle that fit this criteria? Excellent.

This parallelogram has four sides, but no right angles.

This has five sides, which it means, which means it is a pentagon, that has no right angles.

One, two, three, four, five, six, this is a hexagon.

And this goes in here because it has six sides, which means it is four or more.

This shape here, one, two, three, four, five, six.

Oh, it's a different hexagon.

Just different, a different size, just looks slightly different.

One, two, three, four, five, six.

One two, three, four, five, six, they have exactly the same amount of sides.

And this shape here, one, two, three, four, five, six, seven, eight, it has eight sides, which means that it is an octagon, and also has four or more sides.

Now, we have three more shapes left.

Now, can we put them into this circle here? Does this circle, this triangle, and this semicircle have two or more right angles? No, it doesn't.

These shapes cannot go into this section here, which means they just stay on the outside of the Venn diagram.

For your independent task, you are going to create your own Venn diagrams, thinking of your own headings.

So I had four or more sides, two or more right angles.

You might have different criterias.

It could be lines of symmetry.

It could be number of vertices.

It could be number of sides.

It could be whatever you want.

It could be right angles.

So can you please create your own Venn diagram? Can you think of your own two headings? And then sort these shapes into your Venn diagram.

Pause the video when you are ready.

Now, there won't be any answers for this because all of your Venn diagrams could look completely different because you're all going to have your own criteria.

Pause the video now.

If you'd like to share your work with Oak National, please ask your parent or carer to share your work on Twitter tagging @OakNational and #LearnwithOak.

You've done an amazing job today! Let's see what you can remember by completing the quiz.

See you later.