Lesson video

Hello, it's Miss Brinkworth here again.

How are you today? We talked a little bit yesterday about how you may be doing some things a little bit more than you normally do.

Maybe you're watching a bit more TV, but maybe you're also maybe getting to do a bit of cooking? A bit of baking? Maybe you're getting to do a bit of walking or a bit of reading.

Are you managing to do any art, I wonder? Do you get to do any drawing or any painting? We're doing a bit of painting in our house.

So here's a painting that one of my children did.

We're going to come back to that in just a moment because if we look at our learning for today, we are looking at identifying and describing lines of symmetry into 2-D shapes.

We've done lots of work on 2-D and 3-D shapes.

We're going to be building on that knowledge now to look at lines of symmetry.

So what do you need for this lesson? Not very much.

Something to write with and something to write on is all you need.

We're just having a bit of a closer look at that.

We can really see that symmetry is our key learning for today and if you're thinking to yourself at the moment, "I'm not really sure what symmetry is", or if you're a bit stuck on some of that vocabulary, please, don't worry.

We're going to cover a lot in this lesson.

So hopefully by the end of the lesson, you feel a lot more confident recognising symmetry and lines of symmetry.

Okay, so if we look at our warm up for today, a little bit of revision for you.

Could you look at these shapes and decide which ones are 2-D shapes, which ones are representations of 2-D shapes? So not the 3-D ones, 2-D ones.

Imagine giving them a big tick if they're a 2-D shape and then for your challenge, can you pick one of the 3-D shapes and describe it? Remembering to use that vocabulary for 3-D shapes, which is vertices and faces, if you can remember those from yesterday's lesson.

Pause the video here and have a go at those two tasks please, year three.

How did you get on? Hopefully that first question was quite easy and will just get you thinking about shapes again.

So hopefully you were able to see that these three shapes here are 2-D shapes.

Well done.

What about the second part then? Were you able to choose one of the 3-D shapes and describe it using that correct vocabulary? I decided to choose this shape, which is a cuboid, And I decided to choose this one because we see cuboids all around us and I feel really confident in describing the shape because I'm quite familiar with it.

So I didn't pick one of the ones that I thought would be a bit trickier.

I picked one that I felt quite confident with, and that's always absolutely fine if you're given the choice.

So how would I describe my cuboid? So it's got one, two, three, four, five, six faces, six rectangle faces and how many vertices has it got? Can you remember that vertices means the corners? Well, it's got one, two, three, four on that end and it's got four on that end.

So this shape has eight vertices.

Really well done, year three, if you were able to describe one of those 3-D shapes using the correct vocabulary.

Great memory from yesterday.

Okay, let's move on to today's learning then.

We are looking at symmetry.

Symmetry, what is symmetry? Well, if you have a look at these pictures, all of these shapes have got the lines down them.

They're all vertical lines, we've looked at vertical and horizontal.

We'll use those words quite a bit in today's lesson.

So all vertical lines, but they're also the lines of symmetry.

What those lines of symmetry do is they cut the shape in half perfectly.

They are, if we put a mirror on that line, it would look exactly the same, it would be reflecting it and it would look exactly the same.

Let me show you another way.

This is a rectangle piece of paper and it has got lines of symmetry.

What that means is I can fold it in half and it sits perfectly into the other half.

Both of those halves are identical.

They're exactly the same and then I have some lines of symmetry on my rectangles.

This rectangle is symmetrical and there's my line of symmetry, it fits into itself perfectly.

And if I go back to the art that my children made, you probably made these when you were younger, we just put paint on one side, folded it up and gave it a bit of a squish and then when we opened it, it created that symmetrical image.

It's identical on both sides and there's our line of symmetry down in the middle.

So going back to these images then you can see that they show the lines of symmetry.

It's the line, whereas if you folded the shape at that point, it would fit into itself perfectly.

It cuts the shape perfectly in half.

Now, symmetry doesn't have to be vertical, it can be horizontal, it can be diagonal, but in those pictures we can see all those lines of symmetry are vertical.

Okay, but we might also notice symmetry all around us.

This image of a butterfly for example is symmetrical.

We could draw a line down the middle and we'd have two perfectly identical halves.

Where else might we see symmetry all around us? This building here has got a line of symmetry going vertically down it, so does this building.

I wonder whether you've ever seen this building before.

This is the Taj Mahal in India, and it is very beautiful and part of its beauty comes from the fact that it's symmetrical.

We could put that line down the middle and it's identical on both sides.

We could fold it up and it would fit perfectly into itself and we've got a snowflake there is symmetrical and also a starfish and so I started looking around my house to see if I could find some symmetry and I noticed this magazine that we've got has got a really beautiful symmetrical image, piece of art on the front.

You could draw a line down the middle of that picture and it would be symmetrical, it's identical on both sides, but also things like my hair brushes is identical, symmetrical, sorry, I could draw a line right down the middle of my hairbrush and it would be identical on both sides.

I could cut it in half perfectly.

Often when we're talking about symmetry in maths, we're talking about symmetry in shape.

Now these are shapes that we've spent quite a lot of time looking at over the last few days, and hopefully you recognise some of them.

We've got quadrilaterals there.

We've got a triangle, we've got an orange shape, which has five sides.

Can you remember which orange shape, what shape has five sides? That is a pentagon, okay.

If we look at these shapes and we think about their lines of symmetry, we look at that square, for example, that blue square.

It's got a line of symmetry here and a line of symmetry here.

If I just show you why, here's my square and I know that I can fold it in half and it will sit perfectly within itself and there's my line of symmetry and because it's got four right angles, if I fold it again, the other way, it will fit perfectly and I've got another line of symmetry, which you can see there in that picture for that square.

How many lines of symmetry do you think I'm going to be able to draw on that rectangle then? Well, here's a rectangle.

I can fold it in the middle, can't I? And it will sit perfectly inside itself, I've got two identical halves and then I'll have my line of symmetry down the middle there, but that rectangle actually has two lines of symmetry, one horizontally and one vertically So I could also fold it, a bit too thin, I could fold it horizontally as well and cut this piece of paper in half perfectly with that line of symmetry in the middle.

What about the other shapes then? How many lines of symmetry do you think they're going to have? This diamonds, this green diamond in the middle is very similar in line with symmetry to the cube, and to the, sorry, to the square and the rectangle.

It's got two lines of symmetry, the vertical one and the horizontal one, What about that purple shape? How many lines of symmetry do you think that's going to have? Its actually just got one line of symmetry.

It's got a vertical line of symmetry.

Hopefully you can see that if we cut that shape in half, right down the middle there it will sit perfectly over itself.

It would fold perfectly into the other half but I folded it top down, top over bottom, the top and the bottom are not identical.

So it doesn't have that horizontal line symmetry.

What about the pink shape then? It's got three sides so we know it's a triangle.

It's actually a special kind of triangle, which has got a right angle and that means that it's got a line of symmetry here through the middle and that's a diagonal line of symmetry.

It's not vertical or horizontal, it's diagonal.

So that's a diagonal line of symmetry on that triangle there So where you think that last shape, that orange shape with five sides? The pentagon, where do you think its lines of symmetry might be? Got a line of symmetry here down the middle.

So just have a quick look at those shapes as they are all showing their lines symmetry.

But also we can have patterns, just like the one I showed you here on the front of this magazine, can be symmetrical.

So if we look at the next slide, here we have to symmetrical pattern.

We've got two red triangles, we've got two green squares and they are identical to each other each sides.

What about these shapes then? Which one of these has symmetry? What do you think? Which one would I fold up and they would be identical? It's this one here on the left and hopefully you can see the one next to it is not like the mirror image.

It will fold it out and look the same or put a mirror there and it would reflect it perfectly.

That one on the right is not a line of symmetry.

Your turn then, what about this next image? Which one of these is symmetrical? Can you point to the screen and decide which one is symmetrical? Only one of them is.

How did you get on it? It's this one here on the right.

Well done if you were able to see that, year three.

Okay, time for the main activity, I will just go through one of the questions with you just so that you know what you're doing and we'll just explain them to you quickly.

So we're going to do some drawings today.

Can you draw a house which is symmetrical? So it's going to need to have the same thing either side, A flower and a face and then have a go at deciding whether those statements there are always, sometimes, or never true.

Pause the video here and have a go at that independent task part A and B on your own.

How did you get on? Did you find that okay? So your pictures probably won't look exactly the same as mine and that's absolutely fine, so let me just show you what a symmetrical house might look like.

So here we are, here's the house, the line drawn down the middle of it, and you can see that it's got a window on each side and then each side's got half of the door and each side's got half of the roof.

I haven't put a chimney just on one side.

I'd have to put a chimney on the other side as well for it to be symmetrical.

What about flower then? A symmetrical flower, how did you get on with that one? Here's a symmetrical flower, could draw a line right down the middle and it would be identical, either side.

Hopefully you're okay with that one and a face as well, faces as we draw them are almost always symmetrical.

We have an eye on each side, half the nose, half a mouth.

So well done if you were able to draw those, really good.

If you're not sure whether yours is symmetrical, try drawing that line on it, is it vertical or is it horizontal? And does it look the same either side? Where's that line of symmetry? Okay, so what about these statements then? Always, sometimes, or never true? What do you think? Do squares have a line of symmetry? We've looked at that, haven't we? Squares always have lines of symmetry, so well done if you were able to see that.

2-D shapes have symmetry.

Well if we goes back to the slide we did that, we know that some 2-D shapes have symmetry and some don't.

So it's sometimes true.

What about this shape here, then? Do you think this has any lines of symmetry, this arrow shape? That shape does not have any lines symmetry, well done if you were able to see that.

If we drew a or horizontal, or even a diagonal line, it would not have, it wouldn't be the same either side.

It would be different, there are no lines of symmetry in that shape.

How did you get on with part B then? Sorting these shapes into the correct column.

Do they have zero lines of symmetry, one line of symmetry or two or more? How did you get on this? It's quite a tricky task.

So don't worry if you made a few mistakes, that's absolutely fine.

So this triangle belongs here, there are no lines symmetry in that right angle triangle.

This arrow, it's got a double sided arrow has got two lines of symmetry.

This shape here, a rectangle with the corner cut off it, doesn't have any lines of symmetry.

This shape here has an irregular pentagon, it's got five sides, has got one line of symmetry.

Square, we know, has got two or more lines of symmetry.

So well done.

Were you able to add another shape? If you drew an equilateral triangle, where all the sides of the same length, it could go into one.

It goes into the column which has got more than two lines of symmetry.

You could draw a rectangle and put it in that column as well, or you could draw a very unusual shape where the sides are all different and maybe you could put that in the column with no lines of symmetry, so well done if you got onto the challenge there.

Okay, time for you to complete your final knowledge quiz and see how you got on with today's learning about symmetry.

Great learning today, guys.

Well done, have a fantastic day, bye bye.