Lesson video

Good morning, Year Three, Miss Brinkworth here again with Oak National Academy carrying on your learning with angles today.

And like I've been doing previously, I would just like to share a little maths fact with you to get us going today.

Now you've probably all heard of millions.

What comes next? Billions.

And next? Trillions.

Do you know what comes after trillions? It is quadrillions.

And after quadrillions? Quintillions, you might be able to guess I've only just heard that this morning as well.

So little math fact to get us started.

So, today's lesson, we're going to be revising angles.

So we're going to be looking at a lot of the learning that we've done previously in the week with myself and Mr. Etherton, and just revising that angle learning.

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

So a pen or pencil's great, something to write on.

And then that angle, right angle measure as well from the previous lessons.

So just to remind you, that either a piece of paper that's been folded into that sharp corner of a square, or even easier, just a nice corner of a piece of paper, so it could be a scrap piece of paper, a piece of paper from a book, just so that you can use it to measure right angles today.

Okay.

So just pause the video and go and get those things if you haven't already got them.

And also have a go at the introductory quiz which has some revision on those acute and obtuse angles from yesterday if you haven't already done that.

Okay, let's come back together then.

Let's just get you started off looking at angles again.

Get you thinking about angles, have a go at this warm up, pause the video here and just tell me how many angles each of these shapes have.

Okay, nice easy start at first, how many angles do each of these shapes have? Well, that green shape there has four, it's a quadrilateral.

It's got four sides and four angles.

The blue one is a triangle.

Tri means three, three angles.

All triangles have three angles.

Okay, what about the purple shapes then? We need to remember what angles are.

Angles are where two straight lines meet.

It is the space between two straight lines that meet.

Does that circle have any straight lines? If it doesn't have any straight lines, it can't have any angles.

It's got zero angles.

Okay, looking at that orange shape then, that orange shape has got six sides.

It's a hexagon, so six sides.

And so it's got six angles.

Well done if you've got all of those right.

Okay, let's move on then.

And we've got our star words for today.

Now, none of these should be new to you, as we're just revising all of these terms today, but let's go through them together.

We've got angle, equal to, greater, obtuse.

Acute, lines, smaller, 2D shapes.

Well done, just have a look at those and just think about whether you know what they all mean.

Heard them all before.

Remember, we will be revising them all today if there are any that you're thinking, hm, I'm not quite sure I remember what that one means.

We will be revising them all today.

Okay, so we've talked about this briefly, but let's just remind ourselves what we're actually measuring when we talk about angles.

What are we actually measuring? Here's some angles here.

The black lines are straight lines that meet at a point.

So they are angles and we can see that those blue arrows have been put in to show us that we are measuring the gap between them.

So angles are the space between two lines.

Now we've talked before about how we can make angles with our hands.

So we can have our straight lines with our hands, we can make smaller angles, we can make right angles, we can do angle arms as well.

So we can have one arm that goes straight up.

And we can have one that comes out to the side and that would be our right angle.

And we can move them closer together for an acute angle, further apart for an obtuse angle.

So, when we're talking about angles, we're talking about the space between two straight lines that meet at a point.

Okay, a little recap here then.

How many angles are there in each of these shapes? We've done this a little bit in a warm up but there's some more shapes here for you to have a go at.

And if you want a bit of a challenge, you can also have a go at telling me what is the name of the shape.

I wonder if you know all of them.

So pause the video here.

Tell me angles of each shape, firstly and then if you'd like a challenge, what do you think all the shapes are called? How many of them can you name? Pause the video here.

Okay, so we know that a triangle has three.

that shape next to it is a quadrilateral, it might be a square.

It has four.

Well done if you said square, that's absolutely fine.

A square is a type of quadrilateral.

The one next to it, you can see we've got a pattern going on here, has got five angles and is a pentagon.

Well done if you knew that.

Moving on, then, no prizes for saying that we've got six now but can you remember what a six sided shape is called? I remember this one because six has got an X and so has hexagon.

So a six sided shape is a hexagon.

Oh, now we move into some trickier ones.

In terms of names, I'm sure you are perfectly capable of counting the angles on these shapes but what about the names for them as well? So I'm sure that you saw that this shape has got seven sides, this one at the bottom left and a seven sided shape is called heptagon.

Okay a eight sided shape, then.

Lots of people remember this from an octopus.

An eight sided shape is an octagon.

We've then got shapes here with nine and 10 angles.

Well done if you know what a nine and a 10 angled shape are called.

Nine is a nonagon, and 10 is a decagon.

So really well done if you were able to count all the angles on those shapes and you got those numbers correct and super well done if you know the names of all of those shapes, really good.

Okay, let's move on then and we've talked quite a lot about right angles.

So this slide is about right angles.

So coming back to our angle arms, we remember right angled as a quarter turn.

So if we're using our angle arms, we have one that goes straight up and one that comes straight out for a right angle, if you do it the other way around us well.

One that goes straight up and one that comes straight out gives us a right angle.

So, having a look at this here, we could also use our right angle checker for this lesson, for this slide.

So we would want the corner of our right angle checker to fit perfectly into the corner of that shape.

So you'd want the corner to fit in perfectly.

You might need to turn it around to fit in.

But it would fit perfectly if the shape has a right angle.

So have a look at these shapes, pause the video and think about which shapes include right angles.

Okay, as we can see here, right angles are often shown with a box in the corner of the angle and where the two lines meet.

And I've tried to put those in but haven't managed it in all of them to fit the square perfectly in the corner.

I have done on a few of them but a few, the square doesn't quite fit in perfectly but that just to show you is how we normally, that one there in the top left is how we would normally show a right angle but let's go through and see which right angles you were able to find.

So that first shape is a quadrilateral and it's a square or a rectangle so it's got four right angles.

Which are the shapes that got right angles, then? Let's have a look.

Oh, we've got a right angle triangle there.

We've talked about those in previous lessons.

Special triangles have one right angle.

Which other shapes here have right angles, then? This is another quadrilateral here, looks like a square and it's got four right angles that sit in each of its corners.

Can you see any others that have right angles, then? This rectangle here has four right angles as well.

And you can see I wasn't quite as good at putting the corners in those ones perfectly.

The shape down the bottom as well, which is actually a pentagon, it's got five sides but is an irregular pentagon so it looks a bit different to the pentagons we're used to.

But as it's in irregular pentagon, it's got two rectangles there.

Any others that you noticed, I wonder? You've got two here in this shape.

Any more? And another right angle triangle there.

We're back.

So those are your right angles for those shapes.

It's really important and really useful to remember, a right angle is a quarter turn, the corner of a square, the corner of a piece of paper is a right angle.

So try and remember that for the rest of the lesson as well.

Okay, so let's move on to those other angles that we've also learned about this week.

So we learned about right angles and we also learned about the angles which are greater than right angles.

Bigger than right angles so if I'm going to use my angle arms again, I can start at a right angle.

Where my arm goes straight up and straight out and then to make an obtuse angle, I put my arms to come further apart.

Wider, greater, bigger than a right angle.

For our lessons this week are obtuse angles.

So just have a look at that slide.

One, two, three, four, five.

Which of them do you think is obtuse? You can use your angle checker.

Which one is bigger, greater than a right angle? Now we've used our right angle checkers a lot this week to check both right angles and obtuse angles and acute angles, we can use our right angle checker.

And we can also draw on a line that would make the shape a right angle.

Let me show you what I mean.

So if we look at number one, put this red line in, that would make it a right angle and then I can see whether that original angle is smaller than a right angle because it sits inside my right angle.

Or whether it's greater than a right angle because it sits outside the right angle.

Or if it's the same as a right angle because that line matches up with it perfectly.

So for number one, for example, you can see, I hope, that that line and which makes a right angle is greater than the original angle so that original angle there in number one is acute.

Imagine where I might put the red line for the other angles then.

So what I'm doing is I'm creating a right angle so that I can see whether the angle I've got is greater than the right angle, equal to a right angle, or less than a right angle.

So for number two, so number one isn't an obtuse angle, it's acute 'cause it sits inside that right angle.

What about number two? Number two, again, is an acute angle because it sits inside that right angle.

What about number three, then? Number three, it sits outside the right angle, it is greater than a right angle so number three is obtuse.

What do you think about number four? With number four, my line will go right over it because it is equal to a right angle.

And five, what do you think, acute, obtuse or right? What do you think? Again, it sits inside the right angle, it is smaller than a right angle.

So it is acute.

So out of those five angles, just number three is obtuse but we just leave that there for you to have a look at for a moment.

So this is another way of checking whether our angles are acute, right angle, or obtuse.

By lining up that right angle and seeing whether what we've got is bigger or smaller or equal to a right angle.

So let's try that again on the next slide.

We look at obtuse angles here.

We're going to look at acute angles.

Just look at these before we put that red line in.

And just think about which ones of these do you think might be acute? So they're six, seven, eight, nine or 10.

Which do you think might be acute? So let's put that red line in for question six, then.

And we can see that if we create that right angle with our red line, number six is actually greater than a right angle.

It's bigger than a right angle, the lines are wider apart than a right angle.

So six is not acute.

What about seven, then? Seven, we can see that that angle does sit inside a right angle, it is smaller than a right angle.

So seven is acute.

What about eight, then, what do you think? Again, it sits outside the right angle.

It is greater than a right angle.

Number nine, what do you think that one's going to be? The red line sits on number nine, it is equal to a right angle.

And number 10, let's have a look.

What do we think happens here? If we put that right angle in we can see that the original angle of number 10 is greater than a right angle.

So out of those five angles, just one of them is acute.

Just one of them is smaller than a right angle.

Just one of them sits inside that right angle that I've created and that's number seven.

So let's just remember that acute is smaller than a right angle, where the lines are closer together.

Obtuse is greater than a right angle, where the lines are farther apart.

Okay, let's move on then.

Have a go yourselves.

You can use your right angle checker, you could put that line in if you'd prefer.

Which of these are acute, right or obtuse? Can you name these angles? Pause the video here.

Okay, let's have a look.

What do you think, then? So if we put that line in, we can see that this first angle here sits inside a right angle, it is smaller than a right angle, so it must be acute, if we put those red lines in for my other angles as well, let's see where these ones go.

This one is also acute it sits just inside that right angle.

It's not much smaller than a right angle but it is smaller so it's an acute angle.

We know that this one's a right angle, as my red line lines up perfectly.

It's also got that square in the corner, which tells us that it's a right angle.

We've got an obtuse angle here as it's larger than a right angle.

And what do you think, what name is going to appear next to those last two, do you think? You've got an acute angle here, it sits inside the right angle and another acute angle here.

Let's just leave those up for a moment for you to just recap what those mean.

Okay, it's time for your main activity.

So I would like you to, I'll just talk you through what you need to do.

And then it's time for you to pause the video and have a go.

So question one.

Two of those objects down the side there contain right angles, which two do you think they are? You just then need to match the definition, the description with the angle, so which one's right, which one's obtuse and which one's acute? And then there's a little challenge for you there.

So have a go at Part A and Part, so Part One and Part Two of your main activity, pause the video here to have a go.

Okay, let's have a look at those answers, then.

So which two of these objects contain right angles? We have, the boat here has got quite a few right angles, at that point we can see, well, two at least, there and then we have, this lamp has got a lot of right angles there, where two lines meet at a perfect corner at a quarter turn.

So what about matching the angle with a description, right? You can start wherever you like when you see questions like this.

You might decide that you feel really confident with the definition of a right angle.

So it's good to do that one first.

Or maybe it's acute that you feel more confident with and you want to start there.

So let's have a look.

Right is one quarter turn.

We talked about that quite a lot.

Matching the other ones then, we have one which is bigger, which is obtuse and then we have one which is smaller, which is acute.

Great.

And if you've gone on to the challenge, you might have found some acute angles here.

On the corner of what looks like a basket, or a bag, we've got an acute angle there in yellow and we've got an obtuse angle at the top of that first shape there in green.

So well done if you moved on to the challenge question and found those, another obtuse angle there.

And another acute angle there.

Well done if you managed to find those.

Okay, with this here, then, what angles do you think are in purple? Now this one was quite easy, really, because we know that it's, if we have those boxes like that, those squares, put in the corner of angles, we know that they are right angles.

Which angles are pink, then? Now, you should have been able to work out whether these are acute or obtuse.

Are they bigger or smaller than right angles, the pink ones are obtuse, they're bigger than right angles which means that our last one, the orange angles, are acute.

And well done if you moved on to that challenge as well, where you found more 'cause there's lots and lots of angles in that picture so if you did want to do a little bit more work, a bit more of a challenge, keep that picture there and have a go at finding lots more angles in that picture.

You might want to look at the star for example.

What angles can you find in the star there and the arrow there at the bottom as well which we've talked about in another lesson.

Okay, pause the video there and have a go at that final knowledge quiz and have a look at how well you've got on with today's revision of angles.

Thank you very much, well done for all your hard work on angles today and have a wonderful day, Year Three, bye bye.