Lesson video

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Miss Brinkworth here and I'll be carrying on with your angles work today with Oak National Academy.

So I'd like to share some math facts with you today.

And I wonder if you realise that these system of numbers that we use where we've got zero, one, two, three, four, five, six, seven, eight, nine, and with those digits we can make all the numbers that we need is the Hindu-Arabic system which has been around for over a thousand years.

So people have been using maths for a really really long time in exactly the same way that we do.

So like I said, today your learning objective is to recognise right-angles, so it is moving on from the work that you've done with Mr. Epitan earlier in the week about angles.

So let's just have a look at what you're going to need today.

So like normal, you're going to need a pen and a pencil and something to write on, so some paper.

You're going to need one more thing today, you're going to need a right-angle checker.

Now this is really easy to make.

So, you can either just have a piece of paper, as long as the corner on your piece of paper is actually sharp, that's absolutely fine, okay? You just need a corner of a piece of paper, okay? And that can be just a scrap piece of paper, it could be a corner of a book.

We're not going to damage a tool, so you can use a corner of a book, just to paperback will be fine.

If you don't have a nice sharp piece of paper, if you've only got maybe ones with rounded corners, that's not going to be okay, all right? Or maybe you've only got just like a scrappy piece of paper, that's fine, we can make a right-angle checker, it's really really easy.

All you need to do is get your piece of paper and fold it in half, nice straight sharp line, and then fold this in half again, exactly horizontally so that you've got that nice sharp corner.

To check whether it's a right-angle, just make sure that it fits perfectly into the corner of a book or a piece of paper and that nice sharp right-angle corner is what you need.

So either fold or scrap this piece of paper up or just grab a nice sharp corner on a piece of paper, that's all you need for today, okay? So if you need to pause the video there go and get your paper, pencil and right-angle checker, please.

Once you've done that, if you haven't done so already have a look at that introductory quiz which will be a recap from yesterday's lesson.


Okay, let's get those math juices going then, and let's see what you remember.

Have a look at this warmup.

How many angles does this shape have? How many angles? And if you've managed to do that you count all the angles, have a go to the question, what is the definition of an angle? When we talk about angles, what are we actually talking about? Pause the video here and have a go at those two questions.

Okay, how many angles does this shape have? Let's have a look.

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

Well done if you've got that, this shape has six angles, okay? What are we talking about then when we mean angle, what is that all about? Well, an angles is the space between two lines with a shared point.

So where two lines meet at the same point or start from the same point or end at the same point, we can measure that space between them.

When we're measuring the space between two lines we are measuring angles which is what your focus is for the whole of the week.

So when we have two lines like this to meet at the same point, we are talking about angles, okay? So moving on then, today we've got these star words.

Some of them you'll recognise from earlier in the week and others will be new to you.

So I'll say them and you can say them back to me, please.

We've got one quarter, three quarters, turn, right-angle, two quarters, two halves, four quarters and one half.

So this is what we're going to be looking at today and in a lot of detail.

So let's revise.

I wonder if you could have a look at these shapes.

And looking at them carefully, which of these do you think has got the most angles? Which has got the most angles in it? Have a quick look at those shapes, those four different shapes there, and shout to the screen if you'd like to, the colour or the name of the shape if you know it, which shape has the most angles? Well done if you got the green one, and even better if you knew that because that shape has six sides it is a hexagon.

The hexagon there has got the most angles in it.

Okay, have a look at these angles then, they're not in a shape this time, they're angles out on their own.

I'll just let you to have a think, pause if you would like to, which of these angles is the smallest and which is the largest? Pause the video here and have a think, which is the largest angle and which is the smallest angle? Okay.

This one here is the smallest.

If you think about the angle as a gap between two lines, those two lines are closest together.

They're not far apart, they're close together.

That makes up the smallest angle.

Having a look at the other ones.

This one has the angle, the lines of the angles far farther apart, they are farther apart not close together.

They're farther apart, it is a larger angle.

The space between those two lines is larger.

So well done if you got that, we've got the smallest angle there in the middle and the largest there on the left.

Having a look at this third angle then, this is what our focus is going to be on today.

This is a special kind of angle and this is what we're going to be looking at today.

So let's look at that in a little bit more detail.

They are right-angles.

Our focus today is right-angles.

This is what they look like.

Now you could think of it as a quarter turn on a clock.

These are all right angles here, three different right-angles in this picture.

They're in different orientations which means we've twisted them a bit, turned them, but they are still all right angles.

It could be like the quarter of a square, there you can see in that picture.

And sometimes you can see there's a box put in a right-angle.

So if you see an angle like this where there's a box put in the corner of the angle where the two lines meet, that is always a right-angle.

So just take a minute to have a look at these pictures, all of which show right-angles, our focus of today's lesson.

Angle arms then, you might have done this before.

Here is a picture of a person doing angle arms and showing a right-angle.

So you can have a go at this one.

All you need to do is choose one arm which goes straight up, straight up, and the other arm goes straight out.

You've made a right-angle.

This is a right-angle.

You can do it the other way around, one arm that go straight up and one arm that go straight out and you have got a right-angle.

It's a quarter turn.

It's a right-angle.

Have a good look at that person and have a go at home doing your angle arms. We'll be doing angle arms a bit this week.


So if this is what right-angles are like, let's go back a touch.

Angle arms and these images here of right-angles.

They're a corner of a square, they're a quarter turn.

Can you have a go at this picture identifying any right-angles you can see in this picture? Pause the film here, the video here because there are quite a few different right-angles to find.

So have a good look at the picture.

Can you find any right-angles? There are lots and lots of right-angles here.

Maybe you notice this one here at the top of the house is a right angle, but there are lots and lots in this picture, I've circled quite a few of them here, not all of them.

We've got them in the window.

We've got them at the top of the door and at the bottom of the door, we've got them on the letterbox, we've got them on the postbox.

And there if you have a look on the corner of the four that forms a lovely right-angle there in the corner of the four just there.

So we can say that right angles are all around us.

Just have a look around your room at the moment and have a think, where can you see right angles? It is the point where two lines meet at a corner of a square using your right-angle measure that we made earlier.

It's a corner of a square.

It's a quarter turn, a right-angle.

There exist a lot of that in the world around them.

So, having a look at this picture that I introduced earlier, it doesn't matter if the orientation of the right-angle changes, that means it doesn't matter if we twist that right-angle or turn it, it doesn't matter if you make that whole picture bigger or smaller, the right-angle is still a right-angle.

This is still the right angle whether I twist it round, whether I make it bigger or smaller, this corner here still is a right-angle.

Having a look at this picture here we have a rectangle here split up into four sections.

And there's lots of right-angles on that rectangle, on those rectangles.

Those right-angles don't change if we move that rectangle around, the right-angles remain right-angles.

A really important piece of learning there.

Okay, so wrap your angle checker, your piece of paper or your scrap piece of paper that you folded nicely to make a nice sharp corner of a square, go around your room or wherever you are and see what right-angles you can find.

Pause the video here and see which right-angles you can find.

Okay, hopefully you found lots and lots of right-angles in your room, just in my house I can see that the corner of a book when I align my angle measure, my right-angle check up with it perfectly, I can see the corner of my book is a perfect right-angle.

Having a look at that picture on the screen, there's lots of right-angles here too.

Maybe in the corner of a window, in the corner of your window, maybe on a poster or a picture on the wall.

That's on the corner of a bedstead if it's a sharp corner of a square.

On the corner of a desk.

On the corner of your laptop or your computer at home.

Lots of right-angles in the world around us.

Your turn then.

Right-angles exists within shapes.

Can you find all the right angles in these three shapes? And then if you like a challenge, on this shape here there are five right-angles, can you find them all? Have a think about where the right-angles are on these shapes.

Pause the video here if you need to.

Coming back together then, that orange shape which is a square contains four right-angles.

The purple shape which has got five sides so it's a pentagon has got just two right-angles.

Those other angles on that purple shape are not right-angles.

If I used my right-angle checker, it wouldn't fit perfectly into those other corners on the pentagon.

What about that pink shape at the bottom then? That's a triangle.

Does it have a right-angle? It has one right-angle.

In fact, that's a special kind of triangle which is called a right-angled triangle.

It's called a right-angled triangle because it's got one right-angle.

The other angles you can see on that triangle are too small to be right-angles.

The lines are closer together than on a right-angle.

A right-angle is that quarter of a square, a quarter turn, the other angles on that triangle are too close together to be right-angles.

What about your challenge then? Did you manage to find the five on that arrow shape? I wonder.

One, two at the end there just like a square, three, four, and right at the end is a fifth.

Well done if you found all of those, that is quite tricky.

Okay, here's a fact then.

I know that if an angle is a quarter turn it is always a right-angle.

And we taught, already mentioned often right-angles have these squares put in the corner.

So if you see an angle where there's a square put where the two lines meet, it is always, sorry, where the two lines meet it is always a right-angle.

So, if something makes a quarter turn, it is always a right-angle.


So it's time for your main activity.

I am going to want you to pause the video and have a go at the activity on your own but I'll just go through the first question with you.

So, decide which of these shapes have right-angles.

So we'll just do one.

Having a look at that triangle, I just want to have a think about whether it's got a right-angle.

I could use my right-angle checker, I could look at it really carefully and think all those, the corners, sharp square corners, a quarter turn.

I don't think that triangle has any right-angles in it, okay? Think about your right-angle arms as well they might help you.

Straight up and straight out is your right-angle.

That triangle it's angles are too small, they're too close together to be right-angles.

Pause the video, have a go at that and the other section of your independent task.

Coming back together let's have a look at them.

So get us on to the right there.

Okay, so which of these shapes do contain right-angles? We agreed that the triangle doesn't, but the square does.

We know that a right-angle can be thought of as the corner of a square.

So this square has definitely got right-angles.

Which other ones then have got right-angles? That other triangle does.

Although it's still a triangle, can you see that those triangles are different? The triangle that's number one, the angles are much smaller whereas on triangle which is number three, it's got that one angle in the corner on the bottom left which my right-angle checker would fit into perfectly.

We've seen that shape arrow before, we know that one contains quite a lot of right-angles.

And looking at the other shapes.

Those don't have right-angles.

Number five, semicircle and number six which is a hexagon, do not include any right-angles in these examples.

Which one do you think has got the most right-angles? Then that quick challenge.

Well we saw previously that that arrow shape has got lots of right-angles, five.

So that one's got your most right-angles.

Looking at the poppy then, which one is the right-angle below? Hopefully you remembered that if it's got a square in the corner, it is a right-angle.

Also having a look at the other two, number one is too big, the lines on that angle are too far apart to be a right-angle.

If I think about my angle arms, getting that right, there too far apart.

They've gone much wider than a right-angle.

And the same looking at three those are much closer together than a right-angle.

The lines are much closer together.

Then the right answer for question one of part b is that middle one, number two.

And looking at this picture of a castle here circle all the right angles.

Now again, there are a lots and lots and lots of right-angles here, I wonder how many you were able to find.

I'm not sure I found them all because I certainly cycled a lot.

We've got them all the way across the top of those, of the top part of the castle, down the bottom here as well there on the corners here, lots and lots of right-angles.

Well done.

Moving on to that challenge question, draw a shape that's got one, two and four right-angles.

Hopefully you've been able to see from the work we've done today that you can draw a triangle which has a right-angle in it it just got the one right-angle, a right-angled triangle.

For two right-angles, you might want a shape like this which is, it resembled a square at the top.

So it's got those two right angles at the top left and the top right.

But then at the bottom the angles change and those aren't right-angles.

So it's just got the two right-angles.

And the four right-angles, again hopefully you've seen from today's lesson, a square or rectangle contains four right-angles.

Well done if you managed to get some of those questions right.

Really really good work.


Pause the video there and have a go at that final knowledge quiz for today and see how you got on with today's learning.

Well done yesterday, you should feel pretty confident with right-angles now.

And thank you very much for working so hard.

I will see you tomorrow for some work on angles.

Bye bye.