Recognise right angles

Key Stage 2

Maths

Angles

﻿Hello everybody, my name is Mr.keisall and welcome to today's lesson on right angles. Now, before we start, you will need pen a piece of paper and some form of graph paper or squared paper. If you don't have this, you can print it off from the slides. Also, please make sure you've got a nice quiet place around the house, somewhere that you're not going to be disturbed. And don't forget to move away any sort of distractions, for example, turn your phone on silent or move away completely. Now, when you're ready, pause the video, and let's begin. So today's lesson is all about recognising right angles. And today's lesson we're going to start by understanding what an angle is and how big it is. So we're going to look at understanding angle sizes. We're then going to develop our learning by looking at right angles and measuring right angles and then looking at right angles within shapes. After that we'll go through our independent task. And finally, we'll go to our quiz. As I mentioned, you'll need a pen, piece of paper, and some graph paper. So to start with a little bit of revision, we know that an angle means the point where two lines meet. And on your page, you've got some examples of angles where lines meet. You've also got an example of number of angles while you got two lines, but they don't meet. And therefore they don't form an angle. We know that we can get angles within shapes. And again, it's where two lines meet. So how are you learning for today? We're looking at the word turn. You have heard the word turn many, many times when somebody has had turned around or perhaps you turn page, but we need the definition of turn. So turn means to rotate around the points. You need to know that a full turn is 360 degrees. So if you turn all the way around, that is 360 degrees. A half turn is 180 degrees. So if you turn halfway around, you've turned 180 degrees. And finally, we've got a quarter turn, which is 90 degrees. And 90 degrees is what's known as a right angle. In order to look at what is a right angle and what is not a right angle. We're going to make a right angle measure. Pause the video, please have little piece of paper and we'll show you how to do it. So to make your right triangle measure, all you need is a piece of paper. It doesn't have to be like this. It can be a normal piece of paper. But all you need is two folds. Fold number one, again fold in half. And then you get to take that again and fold it, in half. So just to show you, you fold it in half and then half again. And this point here will be 90 degrees. You can check it on a protractor and you can see that It's 90 degrees. You can check it with a different objects. For example, you can check it with the corner of an envelope and you can see that's 90 degrees. You could use something like a book, and you can see that's 90 degrees. Which of these angles are right angles, measuring 90 degrees. How can you check? So when I'm measuring angles,. I'm looking for right angles. I'm going to start with my angle measure, which I made from folding a piece of paper, and looking for the corner. I'm going to place it on the first angle. And I can see this is 90 degrees. It doesn't matter which way I place it, It's still 90 degrees. On my second angle, I can see that if I place it there, it's not 90 degrees. If I place it there, it's not 90 degrees. But this one is not 90 degrees. I can see when I place my 90 degrees angle measure there. This one is bigger than 90 degrees, so it's not 90 degrees. I can see this one is smaller than 90 degrees. I can see this one is bigger than 90 degrees. I can see this one is bigger than 90 degrees. Look at the last one, I can see, this is exactly 90 degrees. We can also measure right angles in shapes. Pause the video and use your angle measure to measure the angles and this shapes. I can use my angle measure again. I know that the first angle is 90 degrees. I know the second angle is 90 degrees. Now the third angle looks like it's 90 degrees but actually this is a curve that does not work for an angle. That is not 90 degrees and it's the same there, the angle is not 90 degrees. On my second shape, I can see that it is 90 degrees. That is 90 degrees. That one is 90 degrees. And the final one, is 90 degrees. And this shape, none of these angles will apply 90 degrees, but I'm going to check anyway, because that one, Isn't 90 degrees, that one also Isn't 90 degrees. Oh, look, this one is actually 90 degrees. So although it's not a regular shape, but a square, it's still 90 degrees. That one is not. That one is not. Now this shape is symmetrical, so it's the same on both sides, so I'm thinking this might be a right angle. Lets check. I'm not going to it is a right angle. So we now move on to the developing learning of today's lesson. Have a look at the shapes on the screen. Which of these shapes include rectangles, and how can you check this? See if you can pause the video. Ideally trying to do this task without using your angle measure. But if you need to use your angle measure, use your angle measure. When you're ready, press play. Okay, you should have realised that the two shapes in the middle, the square and the triangle both have right angles. Also it's worth noting that this is how we show that the angle is a right angle. With most with angles with small semicircle, but with right angles we use a small square in the top corners to show that it's the right angle. 'Cause now that you learned a little bit about right angles, can you have a look around the room and see where else you can find right angles? Pause the video and press play when you're ready. So I'm hoping you found quite a lot of right angles around the room. If I look around my room, I can see a right angle in the corner of the room. I can look over the roof and where the wall meets the ceiling is a right rectangle. When I look at my book, I can see there's right angle in the corner of the book, In fact there's a right angle in every corner of the book. So there's right angles all around you. Try to draw some shapes which have right angles. Also try to use the diagonal guidelines too. And think how do you know that the shapes, actually have right angles. Pause the video and when you're ready, press play to continue. So this task asked you to draw some shapes which have right angles. It also says, try to use the diagonal guides, guidelines too. And how do you know these shapes have right angles? I'm going to zoom in a little bit and show you what I mean by this. So, I now have my first shape, now's needed like a test every single side has a right angle. We know that because it's a square. When I'm looking at the next one. If I put my angle measure on, I can see that it's a square on its side, but how could I use the grid lines, the guidelines to do this. Here on the square, I've just used the guidelines, but here is on a diagonal. So how could that work? Well, let's count it if I'm going two up on one along. So I'm going to two, one. And then on the same here, two, one, I'm going two, one, two, one. So actually these points are the same distance. And I know that because I've checked, and it's a right angle. It's similar here let's have a look. This time, how many am I going up? One, two, three, and one. One, two, three, and one. So because of three and one, three and one is the same, so I know that I'm turning my 90 degrees. And this time I count one, and one, now there I count one, two, one, two. What question is, is this still a right angle, a one, one, one, one, one, one. So actually it is. For your independent task. Try to have a look at this clock and imagine the hour hand, and imagine the minute hand do any of those to form right angles. So have a look and can you find right angles on this clock? I'll just give you one example. If the hour hand points to one o'clock and the minute hand points to 10 O'clock, the angle between those two hands will form about a right angle. So pause the video to complete your task. Then once you've done, press play to continue. In this task, you were asked, there are many right angles when a clock shows the time. I start with the exact hours, such as 3 o'clock, 9 o'clock. Next consider the hours and minutes, for example, 12:16 or 7:22. I'm just going to draw some of these. So in my first clock, I'm going to draw three o'clock. So the big hand is pointing twelve o'clock, and small hand is pointing to three. I can check that with my angle measure to see if it works. Yes, it's 90 degrees. My next example was nine o'clock. So the small hand is pointing to nine and the big hand is pointing to the 12, which is o'clock. And I can see again, that is 90 degrees. The other times I was asked to draw the 12:16, so 12, I mean it's 12 o'clock, but actually 16 means that my clock would look about here. That'd be just a little bit beyond 12 o'clock and my minute hand point to 5, 10, 15, point this one here 16. Now, what I can see is that 12:16, is still have a right a angle. And it's the same for 7:22. So at 7:22 or 22 minutes past is five, 10, 15, 20, 21, 22. So the big hand would point to 22 and the small hand, the hours hand would be at seven, but it would be just after seven o'clock. So instead of being seven, is just after seven. And let's check with the angle measure, I can see that, that is 90 degrees. You can explore this a little bit more. For example, let's say you put your clock here and I'm going to go to the nearest minute. Or draw an angle measure along. Based on that, I think that if I did on the exactly two o'clock now we'll be 26 minutes past. So 2:26 might work, It might be one degree or I don't know. Don't forget if you'd like to, please ask your parents or carers to share your work on Twitter, tagging @OakNational and #LearnwithOak. Of course, now you've to complete the quiz. So that brings us to the end of today's learning on right angles. A really big welcome to all the fantastic learning that you've achieved today. Before you finish, it's perhaps worth reviewing your notes, I'm trying to identify the most important parts of your learning. Well the time is up I have to say is thank you very much for today. Take care and enjoy the rest of your evening.

Recognise right angles

Recognise right angles

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UnitMaths / Angles

Maths