Lesson video

Miss Brinkworth here, and I'm going to be with you all week with Oak National Academy doing a series of lessons on lines and angles.

I thought I'd share some riddles with you at the beginning of each lesson.

So here's today's riddle.

What has a face and hands, but no arms or legs? A face and hands, but no arms or legs.

It's a clock.

Having a look at today's lesson, then.

To identify perpendicular lines.

Don't worry at all if you haven't heard that word before.

You're going to know it really well by the end of the lesson.

So let's just have a look at what you need.

You need pencil or pen and something to write on, and as the same as some of our previous lessons, it would be really useful if you have got a right-angle checker for today's lesson again.

So that can just be the corner of a piece of paper, or it can be a piece of paper which you have folded over a few times.

Just make sure you've got that right angle in the corner there.

So one of those would be really useful for today's lesson.

Okay, a nice, easy question here to warm up with, something that you should be able to do really easily after the last series of lessons.

Can you identify, can you find the two right angles below? I'll be really kind and do some more angle arms for you, to remind you what right angles are.

Remember that right angles are where you have a line which goes, if you're doing your angle arms, straight up and straight out.

It looks like the corner of a book, the corner of a square, 90 degrees, a quarter turn.

Could you find those two right angles there? Pause if you need to.

Well done.

I'm sure this wasn't too tricky for you, but it's a really good idea just to get those maths juices flowing again.

Having a look at this task here, the two right angles are here, B, we can see that that's a right angle.

Often, that little square gets put in the corner of a right angle so you know that that's what it is.

And that's in a nice orientation, there.

That means it looks like the corner of a book.

That's sort of how we expect to find a right angle, but we know that right angles can exist, can still be right angles, in different orientations.

Means we can twist them and they are still right angles.

And D is also a right angle, just in a slightly different orientation, and it doesn't have that nice square in the corner to give it away.

So well done, year three, if you managed to find both of those right angles in our warmup activity.

Okay, let's move on then.

Here are our star words for today.

There aren't very many of them, but let's go through them.

I'll say them, and if you could repeat them at home that'd be great.

So our key one for today is perpendicular.

Then we've got right angle, and line.

Okay, lines and right angles we've talked about in previous lessons.

And like I say, perpendicular is going to be our focus for today.

You're going to really understand what that means by the end of today's lesson.

Okay, so let's revise quickly, 'cause we are building on the work from previous weeks.

So we should know, really well, what angles are, and what right angles are.

So pause the video here and have a little think.

How would you describe to someone, if an alien landed on earth and had no idea what angles are, or right angles, how would you explain to that alien what they are? Pause the video here and have a go.

Okay.

Angles, then.

Let's revise what we mean by angles.

Angles measure the space between two lines.

Intersecting means they meet.

So we have two lines which meet, and angles measure the space between those lines.

So, that can look like this.

Two lines which meet, we can measure the distance between them, and when we do, we're talking about angles.

Okay, right angles.

I've already been really kind to you this morning and shown you right angles with our angle arms. Could you describe a right angle? A right angle is a quarter turn.

And there's a nice angle arms picture there to remind you, as well.

So, that learning's going to be really useful for today's lesson on perpendicular lines.

Here we are, then.

These are all examples of perpendicular lines.

Now, these should look quite familiar to you, and that's because perpendicular lines are where two straight lines meet at a right angle.

Two straight lines meet at a right angle they are called perpendicular.

So all of those there are examples of perpendicular lines.

Just take a moment to have a look at those.

So perpendicular lines always come in pairs, there's always a pair of perpendicular lines, and they meet at right angles.

Okay, using that then, which of these lines below are perpendicular? Can you see which ones are perpendicular? Well, let me have a think.

I know that I need my, I could use my right-angle checker.

I could put that up against the screen, and as perpendicular lines meet at right angles, I know that if my corner fits perfectly, then I've got perpendicular lines.

So let's have a look at which ones are perpendicular.

These ones in the middle are.

So those two lines meet at right angles.

And also, this shape here, these two lines here meet at a right angle.

If I put my right-angle checker in those corners, it would fit absolutely perfectly.

They'd be right angles.

So those are examples of perpendicular lines.

Well done.

Okay, here are those lines again, exactly the same picture as before.

We moved those across, and we're just showing you that you can put those squares in the corner to show that they are right angles.

And if you see that, they will also be perpendicular lines.

Okay, so perpendicular lines can appear in shapes.

Have a think to yourself quickly, which shape do you think is going to appear which shows perpendicular lines? Two lines which meet at a right angle.

Which shape do you think is going to have perpendicular lines in? Which ones do you think are going to appear on the screen? Oh, this shape has some perpendicular lines.

This shape, this shape.

Do we think this shape has perpendicular lines? And what about this one? Let's have a look, then.

This blue shape, here, it looks a little bit like a cross, has got perpendicular lines.

We can see it's got those corners like a square, corners like the corner of a book, where two straight lines meet at a right angle.

It's got a few.

There's just one marked out there in grey, but if you have a look at that blue shape I'm sure you can see that there are other examples of perpendicular lines on that shape.

Which other shape do you think has got perpendicular lines, then? Which one other shape is going to get a tick? Oh, that purple triangle has got two, has got a pair of perpendicular lines.

In that corner, it's like the corner of a square.

And remember we talked last week about how that triangle has a special name.

It's a right-angled triangle because it contains a right angle, and so it contains perpendicular lines.

Well done.

There's one more shape.

Looking at those last three shapes, which one do you think's going to get a tick next to it, on it? Which one do you think's going to get a tick? Well done if you saw that the square has got perpendicular lines.

That green square.

Again, it's got more than just that one that's picked up there in grey.

It's got other lines which meet at a right angle.

It's got other perpendicular lines.

Those other two shapes do not have that perpendicular lines.

Well done.

Your turn, then.

Which ones of these shapes, which of these shapes have got perpendicular lines, and which haven't? Pause here and think: Is that shape going to get a tick for some perpendicular lines, or not? What do you think? Have a go.

Right, let's come back together.

Really well done if you had to go at this.

Which ones do you think's going to get a tick? Well, this green shape is a rectangle, and that has lines that are perpendicular.

In fact, each corner of our rectangle has got lines which meet as perpendicular lines.

This orange shape here has also got those same corners where lines meet, and that means at right angles, which means they are perpendicular.

So those two shapes, well done if you got that right.

Those two shapes have got perpendicular lines.

Let's have a look at the other two together, then.

Do we think these other shapes have got perpendicular lines? If I use my angle measurer, my right-angle checker, will I be able to fit that corner perfectly into any of the corners on those shapes? I don't think I will.

Those shapes do not contain perpendicular lines.

Well done, everybody.

You're doing really well today with this new vocabulary.

Let's move on.

Okay, it's time for you to have a go now, and see what you've learnt, see if you can find those perpendicular lines.

So let's just go through the first part of the activity together, just so that you know what I'm asking you to do.

So for that first activity on Part A, you just need to find the perpendicular lines.

So if you want, you can draw in that little box or you can circle the perpendicular lines.

Now for this question, you've been given the shapes on a grid and that does make it a little easier to see if the corners fit perfectly like a square into the corner.

So if we have a look at that first one, for example, that's a triangle.

Is it a right-angled triangle? Does it have perpendicular lines? Yes, I can see that those two lines there do meet at a right angle, so I can circle them.

So pause the video here and have a go at the rest of the independent activity.

Okay, well done, everybody.

Really good work having a go to the independent activity on your own there.

Let's see how you got on.

Please don't worry too much if you're making mistakes at this stage.

This is brand new learning, and it's new vocabulary for you.

So just keep going.

Even if you've got one or two wrong, just have a listen, have a look, and maybe see how you got that one wrong, and we can get it right next time.

So we've already talked about question A.

It has got that one pair of perpendicular lines there in the corner, because it is a right-angled triangle.

What about the other shapes, then? Let's have a look.

Did you think that B had some perpendicular lines? It has, it's got them sort of in the same corner there as that triangle, where the two lines meet at a right angle.

Well, let's have a look at the other ones then.

Have they all got perpendicular lines? What do you think about C? Did you decide that C had perpendicular lines? It does.

Those lines there do meet at a right angle.

And if you're not sure, again, you could get your right-angle checker, the corner of a piece of paper, and just put it in that corner, put up against the screen if you need to, and just see that it will fit perfectly.

It's on a bit of a different orientation to how we often see a right angle, but remember that as long as your right-angle checker fits in there, it is a right angle and it means those lines are perpendicular.

Okay, what about that shape there for D, do you think that one's got a right angle? It has got one, right at the bottom there.

And that last shape, as well, E.

It says it has more than one.

Did you manage to find more than one pair of perpendicular lines for that shape? So they're down here in the corners, where we can see that shape is very similar to a square or a rectangle at the bottom there.

Okay, this person is saying, "Any two straight lines that meet are perpendicular." Did you think that was true, or do you think it's false from what you've learnt about perpendicular lines today? In this case, she is.

She's not correct.

She's got the false statement there.

Not any lines that meet are perpendicular.

They've got to meet in a particular way.

They've got to meet at a right angle.

Okay, on Part B then, did you manage to find those perpendicular lines that are on their own, not within a shape? See if you managed to find them.

Which ones did you think were perpendicular? Well, we've got these ones here, where they cross and they make those sort of four right angles.

If I put my right-angle checker in any of the corners made by those two lines, I would find right angles.

So those lines are crossing at a perpendicular angle.

There's one more set, as well.

These are also doing the same thing.

It's like the same cross that's just been twisted, but we know that twisting it or changing the orientation doesn't change the fact that they're right angles.

Okay, we've got this person here again now, saying, "This shape contains four pairs of perpendicular lines." What do you think? Does it contain four pairs of perpendicular lines? It's true.

The lines meet at the four corners, so we've got four perpendicular lines there.

Well done.

Okay, do your final knowledge quiz now then.

Pause the video and have a look at how much you've learnt today.

Well done! Some really hard work there, and some brand new learning.

Well done, you did brilliantly.

I'll see you back here for another lesson soon.

Bye-bye!.