To compare and classify 2D shapes

Key Stage 2

Maths

2-D Shape and Symmetry

If I imagine the minute hand of a clock pointing at 12 is a measurement of 0°, what number would the minute hand be pointing at for 180°?

How many more degrees would be needed to make a right angle if I had already measures  37°?

What do each of the angles in a square measure?

﻿Hi there, everyone and welcome to our maths lesson for today. Today we're going to be looking at shape and symmetry, continuing from our previous sessions. And we're going to be looking at comparing and classifying 2D shapes. I hope everybody is really well. I hope you're ready to learn and I hope you are feeling excited about our next journey in our maths learning together. So let's move straight on. Welcome back, so I thought I'd share a few different things over the next few sessions. I gave you some random facts to do with world records before and I've given you some amazing maths facts but I thought I'd show you a few mathematical tricks as well, which might be quite cool. So today, the first one I'm going to share with you is this. Have a look here and it says whenever you multiply six by an even number, so that's two, four, six, eight, the final digit in the answer will be the same as the number you've multiplied it by and the digit in the tens places will be half the size of that number. So for example, have a look at this. Six times eight. So the number in the ones column, if you look, is eight and I was multiplying by eight. And the number in the 10s columns is half the size of the number in the ones column. So half of eight is four so 48. And you can try it with all of them. So for example, six times two. The last digit's going to be two in your answer 'cause we know the answer is 12. And one in the tens column is half of two. It works every time for any single-digit number. So let's take another quick look at one. Let's do, up here, we'll do six times four equals, and can you tell me what six times four is? Yep. 24. And look, four, four. And two is half of four. Eight and eight and four is half of eight. It works every time up until obviously six times 10 and then things start to change. But quite often with your times tables, you will spot patterns like this that will be really helpful and really useful for you. So I thought I'd share that with you to start with today. So make sure you've got the equipment that you need for today's lesson. That's a pencil, a ruler, paper or something to work on, provided by your school and somewhere quiet with no distractions. So here is the outline for the day. We're going to move on in a second to looking at our key learning and vocabulary. And then we're going to do a name that shape warmup. We're going to look at 2D shapes in general and then our main activity will be to compare some 2D shapes and then we're going to move onto our final knowledge quiz just to see what it is that you remembered. So let's move on as ever to looking at our key learning and our key vocabulary. So today, we're going to compare and classify 2D shapes. My turn, your turn with our key vocabulary then. 2D. Regular. Irregular. Square. Rectangle. Oblong. Trapezium. Got to go slow on the next one. This is my tricky word. Parallelogram. Brilliant. Rhombus. And vertices. Excellent, well done. So have a look here. Here's our first part of the session. And we looked at one similar to this previously. I'm going to ask you to tell me a couple of bits of information today. Having a look at the shapes that are all labelled, we've got A, B, C, D and so on. But what you're going to do today, I'll just show you the next slide to help you, you're going to tell me the name but you're also going to tell me the number of sides because what we're starting to look at now are the properties of shapes. And the properties of a shape are the things that make that shape the shape it is. So the number of sides. The number of angles or corners or vertices. All of those are properties of a shape. We'll also be moving on at some point to lines of symmetry. But all you need to tell me today is the name of the shape and how many sides it has. What often helps me is if it looks like it's got a lot of sides, I'll start counting with one and just pop a little line through it or a dot or a tick next to it so I know where I started and I don't double count. All right? And then you're just going to be filling in that information for me. So the name of the shape and the number of sides that it has. When you're finished with that and you're confident with that, come on back. So pause and have a go at your task. Welcome back, everyone, so here they are. Here are our answers. Our octagon is the eight-sided shape. The pentagon has five sides. The great word here is decagon. That has 10 sides. Square has four sides. Parallelogram has four sides. The triangle has just the three, the rhombus has four. The heptagon or sometimes known as a septagon has seven sides. A trapezium has four and an oblong has four. And if you look there, you can see very clearly that probably the most common number of sides that a 2D shape will have is four. We've got lots of variations of four-sided shapes. They all have various specific names. And we'll come onto that more in our next session. So well done for that. Take a look here then. Two more words that we need to know today and they are regular shapes and irregular shapes. And if you just take a look at the images there, we'll start to get the idea. Now, a regular shape, well, the definition of a regular shape is that all the sides are equal in length and all the inside angles are equal. So remember this line that we do? When I do this, that means that the sides are the same length. So if this one is two centimetres, they would all be two centimetres. And then all the angles would be equal within it. Here again you know is a square. So if one side is nine centimetres, they would all be nine centimetres and all the angles are what kind of angle? Can you remember? Yeah, they're all right angles. And then here, every single side is the same. If one side is one centimetre, they're all one centimetre. If one side is 10 metres, they're all 10 metres. So the definition of a regular shape is that all the sides are equal, the same, and all the inside angles, or vertices, are equal. An irregular shape then, well, that kind of makes sense now when we know what a regular shape is. An irregular shape, well, that just means that an irregular shape, it doesn't necessarily have equal length sides. And the angles or vertices within the shape won't always be the same. Some of them might be but not all of them. So for example, here these two are definitely the same length but they're much longer than some of the others. These ones are much smaller. Okay? So they're not all of an equal length. So this one is irregular. Same here. This side is much longer than these two so it's irregular. This one, the angles are not all the same so again, irregular. So if everything fits into a nice pattern and they are all exactly the same sides and angles, it's a regular shape. If there are differences between the lengths of the sides and the sizes of the angles, it's an irregular shape. Okay? It's quite easy to remember in the long run. So let's have a look at some examples. Well, here are some examples of regular and irregular shapes. I'll just give you a few seconds to have a look over there and see which ones are which and then just read the definitions why, the explanation as to why. So take a look at number one. We can see that's irregular because the sides are all over the place really. They're not all equal and neither are the angles within that shape. If it has five sides, what kind of shape is it? What do we call a five-sided shape? It's a pentagon. Now, this is an irregular pentagon because it has five sides but it's not uniform. It's not all even. It's not all equal, it is irregular. So it's an irregular pentagon. Number two, we already explained is a regular shape because all the sides are the same, all the angles are the same. And if you look at number three and number five, so here and here, you can see that they are both irregular shapes because the sides are all various shapes and sizes. This has got one, two, three, four, five, six sides. What do we call a six-sided shape? Hexagon, brilliant. So this is an irregular hexagon. This has one, two, three, four, five, six, seven, so heptagon, irregular heptagon, okay? We can still call it a decagon or an octagon but if it's not all equal, we would all it an irregular decagon or an irregular octagon. Hopefully, that makes sense. It makes sense, right? Excellent, good, glad to hear. So take a look here. This is your next task. All I need you to do is figure out which ones are regular, and you're going to represent with the letter R, and which ones are irregular. You're going to represent those with the letter I. Just label them all regular or irregular. And then I need you to pick one of each type of shape, so one regular shape and one irregular shape and just explain how you know. So for example, this shape is regular because blah, blah, blah, blah, blah. Now, my top tip for you, don't write blah, blah, blah, blah, blah, 'cause that doesn't make sense. I want a proper mathematical explanation. How do you know it's regular? What do you know about the sides of a regular shape? If you've forgotten, just skip back, it's fine. If it's irregular, what do you know about the sides of an irregular shape? And then think to yourself what do I know about the angles, the vertices of regular shapes and irregular shapes? So give me a sentence or two just to describe. And then I've dropped in what vertices are. Vertices are angles, corners. We know what angles and corners are. And we can see them in those shapes. So what I want you to do as well for each shape is just tell me how many vertices it has. So if there are six corners, it has six vertices 'cause it's just another word for the same thing. So fill those in and come on back when you're ready. Welcome back. How was that? It was not too tricky, was it? Hopefully, you managed beautifully with that. I'm sure you did. So let's take a look. You can see then on here that this shape is irregular, irregular, we've got irregular here and irregular here. And also, look, one more right at the end. So you've got one, two, three, four, five irregular shapes and one, two, three regular shapes. And hopefully, you'll have been able to then tell me how many vertices each shape has. And you would have also been able to give me an explanation. So for example, I might say I know that this is a regular shape because all of the sides measure the shape and all of the internal angles, all the vertices are the same size as well. I might say I know this is an irregular shape because not all of the angles inside the shape are equal and the sides are all different lengths as well. That's one way you could word it. Okay. Shall we move ahead? Now, your main task today is all about talking. And you'll notice that I'm trying really hard not to do my usual amount of talk, talk, talk, talk, talk 'cause I know that I do a lot of that. So I'm going to step back today and it's all over to you. Now, this is a really nice activity if you've got someone at home that you can work with on this. Now, your partner, the person you are working with is going to pick one of those shapes and they're all lettered. But they're not going to tell you what the shape is. You have to try and figure out which one of those shapes it is by asking questions that have a yes or no answer. Now, let me put this out here straightaway because I've played this with a class before and there's always one child that just says okay, if I can only have questions that have yes or a no as an answer, this is what I'm going to do. Is it shape A, yes or no? Is it shape B, yes or no? Now, although that's inventive and all that, it's quite smart, it's not helping you mathematically. We want you to be able to use your mathematical language and your mathematical questioning to help you figure it out. So for example, my partner's picked a shape and I might say to them, there's a really quick way of splitting a lot of these shapes. So I could say is it a regular shape? And if they say yes, it narrows it down. I know it has to be one of those regular shapes on there. Then I might say does it have an even number of sides? And if they say no, it narrows it down a little bit more. If it doesn't have an even number of sides, it must have an odd number of sides. So that's one, well, there's numbers on one side, three, it could be but I don't see any three-sided shapes. Five, seven, nine, it could be any of those so then I would ask another question to try and figure out. I might does it have right angles? I might say does it have vertices, five vertices? And if they say yes, I can narrow it down, I know which shape it is. So you're asking questions to figure it out and then once you've managed that, you get a point, keep a little tally chart maybe. Don't do what I always do when I do a tally chart, which is stick an extra mark on every time I put on a mark on for myself and I accidentally put two instead of one. It's not cheating, it's just twisting the truth. I don't know. Then you'll swap. You'll pick a shape. Don't tell them which one it is and they're going to question you. Now, if you look really carefully at the screen here, I've given you a few questions you could ask. It may be that you want to write down a list of questions first, okay? That could help you. If you feel really confident and you know about the symmetry, you might say is it symmetrical? Most regular shapes, you'll spot are symmetrical. But when you have irregular shapes, it's quite often they're not. So you might know that. You might want to touch on that. But I would say stick with talking about vertices, sides and then here's one more for you. Parallel lines. We've mentioned this before. Parallel lines, if you remember, are pairs of lines that no matter how long you make them, they will never touch. So for example, the sides on a square, opposite sides are parallel. They will always stay the same distance apart. No matter how long you make those lines, they will never meet each other. So parallel lines that stay the same distance apart all the time are parallel lines. If they are like that, they're not parallel 'cause eventually, they'll meet, okay? So you could ask questions like that. You can think of lots of questions that you could ask but they must have a yes or no answer. Hopefully that makes sense. And now it's really down to you to do the talking 'cause I think me and my big old mouth, we've done enough. It's over to you. So have fun and give it a go. And if you finish this, why not try drawing and labelling some of your own shapes and playing another round? Enjoy. Now, we're back. So hopefully you had a good time playing that game. Hopefully you got lots of good discussion and not that it's important but hopefully, you won. So this is what you need to do now. You need to pop off and take your final knowledge quiz just to see how you've done today. And then come back when you're ready. So we can say goodbye, ready for next time. Well, guys, I hope you enjoyed this session today. I certainly enjoyed being with you again. And I'm going to try really hard to keep my talk down over the next few days. So if at any point you think I'm talking too much, you point at that screen, you say, hey, Mr. C, too much, move on. Hopefully I'll get a bit better at being quicker and giving you more time to explain. And to explore. So well done. It's been a really lovely session. I have enjoyed seeing you again and I look forward to seeing you next time. So for today, from me, Mr. C, that's all. So bye.

To compare and classify 2D shapes

To compare and classify 2D shapes

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UnitMaths / 2-D Shape and Symmetry

Maths