Lesson video

Hi everybody, it's me Mr. C.

How are you all today? Hopefully you are bright eyed, and bushy tailed, and ready to a bit of maths learning.

So without further ado, let's skip through and see what's happening today.

Well, before we do anything, you know what I'm going to say, this needs to be done first.

So can you make sure you've done our first knowledge quiz and then come back when you're ready.

Welcome back you guys shall we find out something interesting relating to numbers then for today? Well, here it is.

I'm sharing this with you today.

It's just quite an interesting fact, which I was quite impressed by.

I wanted to talk to you today about a building, the tallest building in the world, in fact, and that building is called the Burj Khalifa, which is also known as the Burj Dubai.

And it's a skyscraper in, yep you guessed it, Dubai.

Got that from the name, I guess, and that's in the United Arab Emirates.

Now this has a total height of 829.

8, so let's call it 830 if we round up.

830 metres.

It's pretty amazing.

The roof height itself is 828 metres and then above that there are aerials and antenna, which make it even taller.

And this has been the tallest building in the world since about 2009 when it was finished.

And if you have a look at that little chart on the page here, you can see the red one at the end, this one right here at the very, very end, that is the Burj Khalifa right here.

And there it is.

And over 800 metres tall, if we compare that to the great pyramids in Giza, which we've seen pictures of as well and are huge, look at the difference in height, if you've ever been to Paris or indeed, if you've ever been to Blackpool, you'll have seen the Eiffel Tower or the Blackpool Tower, very similar heights.

It's even bigger than that.

Now I can tell you, I have been to the top of this building.

That's the Willis Tower in Chicago, and I did a very exciting experience where you can stand on a window platform ledge.

And it all tilts out from the very top and you can see right down across the entire city.

Now that was terrifying enough, but if I added another couple of hundred metres up onto that I'm not sure I would have been brave enough to do that.

I think I would have been a bit of a coward there and I would have probably backed out.

A very, very impressive building.

And you should definitely look it up and see some facts about that online.

It's pretty mind blowing.

And with that, with our minds blown, let's move ahead and see what it is that we're going to be looking at and learning today.

So making sure that you're ready for the lesson, you're going to need a pencil, a ruler, a paper, or a book or something to work on, somewhere quiet with no distractions.

I would suggest sitting at the top of the Burj Khalifa, but I'm not sure you'd be able to hold on to your work.

It would probably blow away.

And I don't know if you'd get internet signal anyway, maybe not the best place.

So our agenda for today.

Well, the first part we've done, you've done your knowledge quiz.

We're about to move on though to our key learning and vocab.

And then we're going to look at our regular or irregular warmup game, moving on into symmetry and exploring what it means.

You have a main activity looking for lines of symmetry.

And then a final knowledge quiz to see what you've remembered.

So your key learning today to recognise lines of symmetry in a 2-D shape and remember 2-D means two dimensional so we can measure the length and the height.

All right, our key vocab for today.

My turn, your turn 2-D, regular irregular symmetry symmetrical.

Try that one again.

Symmetrical Brilliant.

And mirror line.

Amazing.

And Marilyn is going to give you a big clue when we're talking about symmetry in a moment.

But before we do talk about symmetry, let's take a look at recapping on something we've looked at before.

Now you have a series of shapes on your screen, and you've also got the little worksheet to go with it.

And all we need to do is decide which ones are regular and which are irregular.

And I wonder if you can name what kind each shape is.

If you can't, don't worry, regular or irregular is enough.

And you're just going to write down in the shape, whether it is regular or irregular.

And let's just recap on what those two words mean.

If a shape is regular, it means that all the sides are the edges and all the vertices or corners are exactly the same size.

So if one side is four centimetres, all sides are four centimetres.

If one of the vertices is 40 degrees, all of the vertices are 40 degrees.

That's a regular shape.

Everything is uniform.

Everything is equal.

And irregular shape just means that the edges or the sides are not all equal and nor are the vertices, the angles, the corners, okay? Regular means everything's the same irregular means it's all over the place and a little bit hotchpotch think of it that way, maybe that will help.

So have a go at naming the regular and irregular shapes and come back when you're ready.

So how did we do? Well, here are the answers.

I will try a little to trick you there because there's actually only really one regular shape and that's down here.

It's got one, two, three, four, five sides, so what do we call a five sided shape? Yeah, that's a regular pentagon, pentagon, five sided shape.

Now there are others I've put on there to try and trick you because some people think that they are in fact regular shapes, even though they're not.

So let's start up here, this is an isosceles triangle.

If you remember, isosceles means that two of the sides are equal and two of the angles are equal, but not all of them.

All of them would mean that it's an equilateral triangle.

Then if it's an equilateral triangle, then it is regular.

But this is a pesky old isosceles triangle, so it's not.

And then we have our parallelogram, opposite sides are equal, but the angles are not.

Opposite angles are equal, so they're not all the same.

That's sometimes tricks people because some shapes have got specific names like a parallelogram.

People just assume that it's a regular shape and that's not always the case.

Let's have a look at this one, that one we can clearly see this one is irregular.

But I wonder what kind of irregular shape it is.

Let's see how many sides.

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

It's an irregular octagon.

This one again has a particular name, it's a trapezium.

And people often think it is a regular shape because it has a name, but it's not because look, the angles, they're not all the same, nor are the length of the size.

This one we can see as much shorter than this one.

Here we've got one, two, three, four, five, six sides.

And actually the sides are all the same length.

However, the angles, the vertices are not.

We can see that this one, this one, and this one are clearly bigger than the bottom too.

So that is also irregular.

We've got one, two, three, four, five, six, another six sided shape.

Clearly irregular.

That one is a crazy one.

Here, we have a kite because it has a name.

People think it's regular, it's not.

Look these two sides are much shorter than these two.

And the angles are all very different.

Opposite angles are the same.

So the only regular shape we had was this one, our regular one, two, three, four, five sided shape, a regular Pentagon.

Now I was thinking I might have caught you out there.

Did I? Or did you beat me at my own game? I'm pretty sure you would have done.

So well done.

Let's move ahead though.

So today we're looking at symmetry.

Well, what is symmetry? Well, symmetry is everywhere actually.

You see symmetry all over in nature.

You see symmetry in flowers.

As you can see who you can see it in a lot of animals, for example, butterflies often have symmetrical patterns on their wings.

I know we often just draw them in quite cartoony ways, but actually they do often have those symmetrical patterns.

All right, symmetry makes me feel really comfortable.

I love things to be symmetrical.

If things aren't symmetrical and they're a little bit wonky, it makes me feel a little bit wonky.

And anyone who's ever been in a class of mine will know that I'm forever straightening the tables and getting just right, because I like symmetry.

We're programmed to spot it as well.

There's a lot of it in nature, one thing that people often do think though, is that your face is symmetrical.

What would be really interesting is if you held very carefully a mirror down the middle here and looked at your reflection so that you have two of one side and then try to another side, you'd see two very different faces.

And there were some apps you can do that on as well.

One half of a face is actually very different to the other side.

Even though when you're looking at it, you think, oh, I'm pretty symmetrical.

If you were symmetrical, you might look a little bit like this tiger guy here and look a bit like a cartoon actually.

So it'd be very strange to be symmetrical.

Symmetrical just means that something is the same on both sides, or it may also be that you have two mirror lines and it's the same in all four.

What we call quadrants.

Now, a shape has symmetry if a mirror line, a dividing line can be drawn onto it to show that both sides of the shape are exactly the same.

And we've done this kind of thing when we're much younger.

If you think about it, you've probably done a piece of art where you've had a large piece of plain paper.

You've drawn a butterfly.

painted, sorry a butterfly half of it folded it in half and squished it down and opened it up and had a whole butterfly.

That is a perfect example of what symmetry is.

So if you can remember doing pictures like that, you've explored symmetry, okay? If you take a look at the pictures on this page here, you can see that I've drawn a dotted line down the middle of both of them.

There's our dotted line down in the middle of our tiger, the pink totted line here and the yellow dotted line down the middle of our butterfly.

And that is the mirror line.

And that just means if I were to cut these out very neatly and fold them on that line, the two sides would match up perfectly because they are symmetrical.

If, for example, this eye was red see if I can quickly colour it in red.

Oh, looking kind of angry on one side.

If this side were red to make it symmetrical, I would also have to colour this eye in red.

Okay.

Now, it's symmetrical.

If he had a little smiley bit here, you'd have to have a little smiley bit there going in the opposite direction, it's symmetrical.

If he had a fung here, you'd have to have one here and so on.

Okay, if I added a star, I'd also have to have a star in this one to make it symmetrical.

These are really basic, simple examples of what symmetry is.

As the sessions go on, we'll look at more complex examples and we'll do the same today.

We're just starting basic and we're going to build our way up.

So symmetry basically is when you have split something down a central line, a mirror line, so that both sides are identical.

So look at these shapes.

I just want you to take a few seconds to think what's the same and what's different.

How many lines of symmetry do you think they'd both have.

Let's look at them, shall we? Let's just be systematic about it.

Let's have a look at the top one first.

Now the first thing that stands out to me is first of all, I know the name and I know the name because of one thing that I've spotted and that's the number of sides.

And let's look at all of these sides, all of these sides are in fact the same.

So what kind of shape is this? This is a regular shape.

What about this one, are all the sides of the same? Okay.

So if they're not the same, what kind of shape is this? That is an irregular shape.

And if we look at the angles in this one, the vertices are all worth the same.

And this one though, you've got varying sizes.

Now, if we think about this one and I were to very, very carefully, just have a look straight down the middle here.

Imagine I picked this shape and cut it out, and then folded it, along that line, these two sides would fold up perfectly, almost like the closed wings of a butterfly.

And can you see where we started? I started in the middle of one of the vertices.

So if I've done it with this one, and I know everything is the same on this shape, how many more times could I start a mirror line in one of the vertices? Have a think.

How many vertices are left? Okay, well, let's take a look, shall we? Look at this I can go through each one of these vertices in a straight line to the middle of the opposite side.

And that if I folded along that green line, this side would match up perfectly with this side.

If I turned my head and folded it along the purple line, this part would fall perfectly over the top of this part.

So let's have a look.

I've got one, two, three, four, five.

Can I count this one again? No, I've already counted it once.

Same here.

Same line, same line, same line.

So this five sided shape because it is regular has one, two, three, four, five lines of symmetry.

What about this pesky little number here? Well, partly because it's irregular, and not just because it's irregular because some irregular shapes are symmetrical, but this one unfortunately is not, no matter where I draw a line.

If I fold down the middle here, I'm going to have this little bit sticking up on this side.

If I fold down here, I'm going to have this bit sticking up over there.

So this one has zero lines of symmetry.

Whereas this one has five, five sided shape, five sided shape, two very different numbers of lines of symmetry.

Hopefully that made sense.

And you're going to be able to prove to me whether or not it did by taking a look at this now.

Look at them.

What's the same and what's different? Think about what we just talked about on the last slide and see how that helps with this one.

What's the same, what's different.

And when you've done that, I wonder if you can figure out how many lines of symmetry each shape might have.

I'm going to give you 10 seconds, give it a go.

Five seconds left, three, two, one, and your time is up.

Let's then skip ahead and see what I came up with.

I wonder if we came up with the same.

Well, let's look, shall we? First of all, which of these shapes was regular? Was it the top or the bottom? Brilliant.

This one was the regular shape, so this one must have been the irregular shape.

So look where I started again, I started in the corners, but this time I could join one of the vertices to the opposite one.

So let's count them.

I've done them, different numbers, different colours.

So we can spot them.

One, two, three, four, five, six, and then I've done all of these.

I can't count them again.

So this one has six lines of symmetry and one, two, three, four, five, six sides.

Interesting.

What about the one underneath? Any lines of symmetry? None.

Six sides.

One, two, three, four, five, six, but no lines of symmetry this time.

I will just stress again though, just because it's an irregular shape that's not the reason it doesn't have a line of symmetry.

There are some irregular shapes that do have lines of symmetry, so don't let it regular fool you.

Okay, that's often a mistake that people do make.

You won't be one of those people because you are fantastic.

So how to look at these.

Now each shape has got two dotted lines on it.

Only one of those lines on each shape is a line of symmetry.

So what you need to think to yourself is if I were to have this on paper in front of me and I cut the shape out and folded along each of those lines, which one of those folds would mean that my two halves neatly overlapped? I'm not looking for any fluffy bits on the edge, any bits sticking out, I'm looking for a neat overlap.

So which of those lines on each shape would mean that you'd folded it with a perfect line of symmetry? Have a go come back when you're ready guys, and we'll look at your answers.

And welcome back.

Whoa, came up quite big there, didn't I? Sorry hope I didn't scare you.

Well, let's have a look at the answers you came up with and compare them to the answers that I had.

And I'll show you which ones I thought were the perfect lines of symmetry on those shapes.

Here they are.

So on our first shape are one, two, three, four, five, six.

Should we count it again? One, two, three, four, five, six, seven, eight.

How can I remember to count it easily and carefully? Just mark off the first one I did.

So one, two, three, four, five, six, seven, eight is an octagon.

And which of those lines, well it was this one down the middle, if I folded along that line there, I'd have a lovely, neat line of symmetry.

Okay, let's have a look at this one.

This is our oblong.

Now lots of people think I can go diagonally here, but actually these two corners, these two vertices would not meet up.

If I went along this line.

If I however, went along the horizontal line in the middle, I would have two perfect halves, one on top of the other.

Nice and neat.

So that would be our line of symmetry there.

On our trapezium, it's the one that goes straight down through the smallest edge to the opposite edge.

Pentagon, we've got one here that goes from the top corner, straight down to the middle and you should have gotten that one quite quickly.

Because we did look at that in our example, this is the correct line of symmetry here.

So these two corners, these two vertices would meet up.

Otherwise, if I fold it here and this point would be over here poking out.

And our final one, our six sided shape, which is a.

Hexagon going from vertices.

One of the vertices slightly to the other vertices.

One of vertices is opposite.

So vertex to vertex, opposite sides, opposite angles.

There's our line of symmetry.

There are others, but out of the two lines we had they were the two.

They were the ones in each, okay.

So well done, if you managed to get them.

So take a look here.

I'd like you to think about how many lines of symmetry each of those shapes have.

Okay.

What I think would be really good for you to do, is just get used to looking at where they might be.

And if you think you know where they are just very lightly, I want you to draw on the shape, just draw them on.

Otherwise you can just count them on the screen.

That's absolutely fine.

If you don't have anything in front of you to physically work on, you can just count them on the screen as well.

Think to yourself, am I regular or irregular on this shape? That will also help you with your judgement.

So I'd like you to write down how many lines of symmetry each shape has, and just write that on there with the shape.

When you're done, come on back and let's have a look at how you did.

And your time guys is up.

So let's take a look at how you did with your answers.

So let's take a look, shall we? In our first shape here, I've only got one line of symmetry.

And I think it's quite clear where that one is.

My line of symmetry here goes through this angle straight to the opposite side.

And it's actually a very similar story on this one, straight through here.

There's my line of symmetry.

This would be my mirror line.

And this one, I have five lines.

And if you remember, we've already looked at this, I'll just do a couple.

We've got our pentagram and on our pentagram we go straight through here, straight down there and it would repeat through each one of the vertices to the opposite side.

Here we go.

Can you spot where the other two would be? Yup.

Through here, dot, dot, dot obviously you would have done it much neater.

And our final one would go, there, so five lines of symmetry.

This one would have seven going from vertex to the opposite side and so on.

Here, we would have two lines of symmetry, one going through here and one going this way.

It's an irregular shape, don't forget.

Eight lines of symmetry this time.

One, two, three, four.

I know from calling a five, six, seven, eight, no lines of symmetry on this little number here, sneak that it is.

And again on this one, no lines of symmetry.

Which were the regular shapes, did you spot them? You would have had regular, regular and regular.

All the rest of those shapes are all irregular shapes.

So well done, if you managed to spot them.

If you didn't, don't worry.

Just have another look.

Sometimes it just takes a bit of a second look to see where those lines of symmetry lie.

So next part of your task you've got, and I'll just skip through quite quickly.

The alphabet there kind of a blocky alphabet.

Let's think of it as the Minecraft alphabet.

What you need to do is see if you can figure out where there may be lines of symmetry in each of these letters.

And I'm going to give you a freebie to start with.

I'm not going to mark it on.

I'm just going to show it with my laser pointer.

Look, if I drew a line down the middle of my letter, A, and then folded it over, that would be a perfect fold.

If I did it across my letter C, that would also be a line of symmetry.

What lines of symmetry can you find in our blocky Minecraft alphabet? Now some of them will also have diagonal lines of symmetry.

That means not just going from top to bottom or left to right, and going from bottom corner to top corner or the other way around.

So look very carefully, mark them off.

I'll see you very soon.

Well guys, how did you do? It's a tricky one actually, wasn't it? There was one letter that I was really unsure about and I had to keep looking and keep going over and over and over again, because I was convinced it had some diagonal lines of symmetry.

I don't think it does.

So should we just have a quick look at those? Some of the lines of symmetry that I found were these.

So my letter B, my F and my G had no lines of symmetry there, poor things.

My letter H had two, one going down and one also going across.

Yeah.

And then my I also because it's very similar to the H when you just turn it around.

Two lines of symmetry, nothing for my J got a nice line there on my K.

My M, and then this was my pesky one.

This was the one that was driving me crazy.

I was convinced that it would have also had diagonal lines of symmetry.

But it wouldn't unless the O was more of a square shape because it's an oblong.

And we realised earlier in a previous set of questions, I gave you on here that the oblong actually doesn't have diagonal symmetry.

So this one only has two, one, two.

My Q has a lovely diagonal there, nothing on my R.

Nope.

Here's one, here's one.

Here's one on my V, my W, look at the X, loads going on there.

My Y and nothing on my Z.

Well, brilliant.

Hopefully, you did really well on that.

I'm sure you did.

I find this kind of thing really fascinating after I did it once, I went back and I kept looking and thinking to myself, well, I wonder if we could make patterns using these symmetrical letters as well.

Well, before we disappear for the day, you know that now it's time for you to take your knowledge quiz for the final part of the lesson, so do that and then come on back.

Welcome back you guys.

Brilliant effort today as usual.

So very big, well done from me.

And we're looking forward to doing some more symmetries something I really do enjoy doing, I guess it's because I'm a bit arty and I like art and pictures and stuff.

And so the symmetry kind of gets all those juices flowing.

So very well done.

So until I see you next time, that is all from me.

Mr. C, signing out.

See you soon.

Bye.