How many lines of symmetry?

Plenary Quiz

﻿Hi there everyone. It's me Mr. C, hope you're all well and hope you're all ready to learn today just like I'm ready to do a bit of teaching. Shall we see straightaway what it is that we're doing and then move on to our amazing maths facts for the day. Let's do that, shall we? Well, you know what's coming up first first thing you need to do is this you need to make sure that you've done our Knowledge Quiz. And when you have, come on back so that we're ready to move along. Welcome back everyone. So let's take a look, shall we? At our maths fact for today. Well, as of the fifth of June and I loved researching this one because it's made me feel young again. As of the fifth of June 2020 the oldest living person in the United Kingdom was Joan Eileen Hocquard. And she was born on the 29th of March 1908. So she is now, well as of the day I made these slides 112 years and 68 days old. That is an astounding 40,948 days old. That's a lot of days to have been on this earth. It's a lot of days to have seen things change in this world. Imagine all those amazing inventions that she lived to. She was alive even before and I know this is going to shock you mobile phones and the internet. How did we ever survive before that, aye? So what an amazing feat to have lived for as long as that. Looking at that cake, I think I would struggle with and I'd also have the fire brigade on standby just in case 'cause that is a lot of candles there, well a lot of things could go wrong. But how amazing is that? 112 years and 68 days, it's me feel like a baby again so it made me feel really happy researching this one All right, enough about that though. For today's lesson these are the things you're going to need your pencil, your ruler, paper or something to work on and somewhere quiet with no distractions so no big birthday celebrations please. Put them to one side, if it is your birthday if it is, happy birthday guys. And be ready to work. So here's our outline, our agenda for today. Knowledge quiz you've already done which must mean that the next thing we're moving on to is your key learning and your vocabulary. We're going to follow that with our yes, speedy tables, it's our times tables day. The recap then on symmetry looking at diagonal lines today. Then our main symmetrical activity the challenge activity at the end and a final knowledge quiz to see what it is that you have remembered. So our key learning today. Today we're going to be learning to complete a simple symmetrical figure. And our key vocabulary are the words Symmetry Symmetrical Diagonal Mirror line Reflection Grid and finally the one we keep coming back to 2-D. And if you can remember what the D stands for in 2-D. Yeah, dimensional. And that just means that there are two dimensions that we can measure on a 2-D shape and they are yap, length or width and height. Well done. Alright, shall we crack on? Here it is. Here is your time tables speed challenge. This is something you are really good at I'm sure. If you're anything like me you would try make it easy on yourself by filling in the ones that you definitely know first so I would do my tens first I would do my elevens first because that pretty straightforward. I will do my twos and I would also do my fives first, okay? See what you can do, see how quickly you can do it keep a score of your time and see if you're beating your last time. Good luck guys. Fingers crossed, toes crossed, everything crossed. Off you go. Hey, how was that for you all? Did you manage? Did you get your task done? Did you get through those answers? And did you get them right? So many questions. So let's see, shall we? Here are your answers. So take a look at those zoom on in on those and just check. If there's a particular table again that's tricked you, that's caught you out. Just put a little circle around that or underline it or highlight it so that you know to go back and practise. Practise, practise, practise. Sometimes I find making round songs helps. Sometimes I try and find ways of working them out quicker if I know my two times table, must know my four times table. If I know my fives, I must know my tens if I know my threes, I must know my sixes and it should help me with my nines. They all help you with everything. So have a look and just check if you've got them right. I certainly know there will be people from my class who would have smashed it there or some people in my class that before I've even picked up my pens our pen or pencil and finished the first two columns they've done the whole thing already. So just cast your eyes over those answers. All right, let us move on, shall we? So just to recap then this is a basic explanation of what symmetry is. Symmetry is that one line that you can draw through a shape. That means when you fold the shape the two halves will be identical. Or without folding the shape, if you're looking at it you can see that both halves are identical. So again, I'm going to bring you back to our butterfly as our example. If I'm looking at my butterfly there I can see that this wing is exactly the same as this wing in reverse and the same here and here. Look even the antenna, they're exactly the same just moving away from that mirror line. Same with our tiger face, our friendly tiger. Remember, if it were symmetrical and it had teeth here it would also have to have teeth here that matched it to make it symmetrical. If it had two whiskers you would have to have two whiskers there. If it had a curly hair on the end of its ear you would have to have a curly hair on the end of this ear as well. It will keep going. Symmetry just means that the two pieces reflected in each other are identical. So, today we're going to be looking at diagonal symmetry so we know different types of lines. Let's just recall what they're called. When a line goes straight across that is a horizontal line. A horizontal line goes across. If a line goes from top to bottom or bottom to top it is vertical. If it goes from corner to corner like this one or this one, or this one, or this one then it is diagonal. Diagonal just means corner to corner. Okay? Those are diagonal lines and if you look at these shapes you can see that if I folded along this line this part here would fold over completely to match the top part. And the same here, if I fold it along this line these pieces would fold over to match exactly with this one. Okay? So each of these shapes I wonder how many lines of symmetry we can see. They have one, two, three four, I'm I going to count this one? No, 'cause I already have. This one, no, because I already have. This one, nope. And this one, already have. So this one has four lines of symmetry let's check with this one. One, two, three, four I'm I right to say five, six, seven, eight? No, because look we've already used each of these lines. So again, four lines of symmetry. So a diagonal line goes from corner to corner we're going to come across some of those today. We're going to see that some of the shapes that we're looking at and some of the patterns that we're looking at today will have horizontal, vertical but also diagonal lines as well. So just be watching out for those 'cause they can be tricky. So, take a look here. Look carefully now these patterns and can you see that they all have at least one diagonal line of symmetry? If we look at this one, for example they're not all marked in by the way. But if I look at this one and go from this corner and draw my line through here to this corner I'll see that when I fold it there's a line of symmetry. So if I go from here to here keeping neat obviously. That's a line of symmetry. The same this way. It does have a horizontal and a vertical line of symmetry as well. But look at these ones can you see those diagonal lines of symmetry in there? Faintly marked in green on these ones. So many shapes, many patterns many figures will have diagonal lines of symmetry. Corner to corner, vertex to vertex you're joining up to vertices, okay? So have a look here. Nope, this is not an optician's eye test for you. I'm asking you to see if you can spot any of those letters that have got diagonal lines of symmetry. Now, if you've got an amazing memory you remember from two sessions ago we looked at these and I gave you all the lines of symmetry on the slides however, you're going to be super honest and you're not going to skip back. Just have a go first. Which of these letters do you think have diagonal lines of symmetry? Have a look. Visualise, think to yourself if I fold them will the pieces match up? Give it a go, take a look, here they are. Okay, guys. So here were your shapes, your letters. Which ones did you think had diagonal lines of symmetry? Remember, there was a one I've put it on there because it was from the other session it was the one that tricked me a couple of times that got me a little frustrated. These were the only two that actually had diagonal lines of symmetry. And which one of those two had the most, do you think? Yeah, the X has more lines of symmetry that are diagonal 'cause we've got one from here to here, that's one then from here to here, that's two. Whereas the Q just goes through this bit so it only has one. So this one has one diagonal, and this one has two. This one also has a vertical and a horizontal as well. So the X is pretty greedy, keeps all those lines for itself. Now the O was the one that caught me out several times. The O was the one that I found tricky that I thought had more lines of symmetry and I thought had diagonal ones take a look at it. Does it have diagonal or not? I don't think you'll find, no. No diagonal lines of symmetry at all. It's a tricky one. If it were more square, then yes it would. But because it's rectangular off because it's an oblong, no. So, your first bit of your moving on task then is I've started some patterns here for you. And what I'd like you to do is complete the patterns here using the mirror lines. Now some of them are diagonal some of them are horizontal, some of them are vertical. And one of them I've done instead of looking at squares, like we always do I've put on a different grid view which is full of triangles. Can you complete those symmetrical patterns the symmetrical objects, the symmetrical figures? have a go, and come back when you're ready. And, we're coming back. How did you find that? Did you manage to find the symmetrical patterns? Did you manage to complete them? Should we take a look? Let's do that, shall we? So this time as well I've managed to do them the same colour so that you can see clearly how it's symmetrical. So each of them I have completed for you. Here are my two diagonals and there was another diagonal here. Now the mistake that some people make is they think that because the triangle is this way when it goes over there, it would also be that way but don't forget it's the reverse it's almost like looking in a mirror. Working your way through, checking those answers. Well done. All right. You guys are smashing this, you're really good. So here's the next part of our main task. I wonder how many different symmetrical patterns you can make on these three by three grids. Remember it does help to show where the mirror line is. You don't have to but it does help. So for example, if I wanted to do this one here I'm going to give you a freebie look. If I shade in this square and I've decided I'm going to have a mirror line here. I would also then have to shade in this square. If I decided to shade in, in this half here let me do it, I also have to shade in this half here. And let's go crazy, let's put another one in. Here's my third. That is now we can see symmetrical. What if you challenged yourself? What if you had two mirror lines? If I shaded in this one it would mean it would have to reflect here and here, and here. What if I had a diagonal? You don't always have to do squares by the way you can do triangles like I did. So if I shade that in they'll be another there and so on. Give it a go, see how many you can come up with on these three by three grids. It's not tricky and it's just now about you being creative and showing what you know. Have a good, colour those and see how many you can fill in. Okay? So, come back when you're ready. And I'll see you very soon. Three two one and we are back. So, how creative did you get? Let's take a look, shall we? I'm going to do a couple more. I'm going to try and be brave now and do them without having a mirror line. I don't know why I'm going to start with this one just because it's in the middle. I'm going to shade some in. And I wonder if any of you got the same ones. So I'm going to do this one and this one. I'm also going to do this one, and this one. Can you see where my lines of symmetry would be? So I would have diagonal and also diagonal. I would have a vertical straight down the middle and a horizontal, straight across here. What about this one? Why would my lines of symmetry be here? Well, I've got my diagonal and I've got this diagonal. Do I have a horizontal and vertical? Nope, because if I had one here I'd have to reflect this over the line. And same with that one. Oh, let's try another one. Here you go, that's symmetrical. What about this one? I've got one two three and four lines of symmetry again. And you could just keep going. And you could come up with so many different designs. If you've been really smart and you'd wanted to go away and really challenge yourself you could have probably gone away and found some colours as well and done it in maybe two or three different colours. So, now that your mind is all warmed up let's take a look at our final challenge for today. And here it is. Now what you say? What's going on here, there's no grid? Well, no there isn't. This is to see how well you can visualise something that is symmetrical. So let's take a look, a closer look at this. You have two of the same shape but this time, I've got one with a horizontal and one with a vertical line of symmetry. Well, you're going to do is complete them spice it up and try and use a bit of colour if you can. So for example, if I were to shade in this shape here and you're going to do it so much neater than me. My electronic pen isn't that neat couldn't get into the edges properly. If I tried it in this time, here's my line. It would have to reflect down to here. So now I'm symmetrical again I wasn't a second ago but now I am again. If I did this little triangle here I'd have to think, "Okay, where would that reflect to?" It's going to reflect straight across that mirror line to here. I might then want to do the same on this side. Which means that we'll have to reflect across the mirror line. It's now symmetrical. Can you create two different symmetrical patterns? Give it a go. And come back when you are ready. Okay folks, how did you manage with that? It was a little trickier on those backgrounds, wasn't it? With the different grids So let me just come back to the one I was looking at and we're going to just continue a little bit more. If I wanted to add a bit more in here I'm going to do this one now look, I'm going to go here. If I shaded in this part and this part It means I'd have to do straight opposite on that mirror line. Like so. I might decide I want to do this one and also this one which would then mean I'd have to go opposite. So and like so. And it's no different with this one. Let's try here, and here but this time remembering my mirror line is down the centre from top to bottom, it is a vertical one so I've got to flip over this way. And so on. Okay, let's do oh, let's go with this one. So it must be there. This one, so it must be there. And so on. Guys very well done. If you managed to work your way through those with no problems, then you're an absolute megastar. Big thumbs up. So, have a go on our knowledge quiz. And then let's get ready to say goodbye. Great day guys. Very well done. Good job with all your hard work. Hopefully you did all right in our final knowledge quiz and that is it from me, Mr. C. So I will see you next time. Ciao. Bye guys.

Which letter DOES have a line of symmetry?

Which letter DOES NOT have a line of symmetry?

Which shape does NOT have a line of symmetry?

How many lines of symmetry does an equilateral triangle have?

How many lines of symmetry does the number 8 have?

To complete a simple symmetrical figure

In this lesson, we will deepen our understanding of symmetry by creating our own symmetrical figures and completing others that have been started. We will learn how to check our work to ensure that lines of symmetry are accurate and we will use the correct vocabulary to explain our figures.

Maths

Y4 Maths

Key Stage 2

Year 4

2-D Shape and Symmetry

Geometry

THEME

UNIT

Shape and symmetry: To compare and order angles

Shape and symmetry: To identify right angles

Shape and symmetry: To identify acute and obtuse angles

Shape and symmetry: To investigate angles within shapes

Shape and symmetry:Identify angles within shapes

To compare and classify 2D shapes

To compare and classify quadrilaterals

To identify and classify right angled and equilateral triangles

To Compare and Classify Isosceles and Scalene Triangles

Quadrilateral Problems

To identify lines of symmetry in 2-D shapes

To identify lines of symmetry in a pattern

To investigate a problem using symmetry (Part 1)

To investigate a problem using symmetry (Part 2)

How many right angles does this shape contain?

Estimate this angle. Which guess is closest?

What do each of the angles in a rectangle measure?

What kind of angle is less than or equal to 45 degrees?

What kind of angle is more than 90° and less than 180°

How many degrees on a straight line?

Which angle is the odd one out?

Angles in a triangle add up to how many degrees?

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°?

Lesson overview:To complete a simple symmetrical figure

Core Content

2-D Shape and Symmetry: