Video: Reasoning with number bonds

﻿Hi everyone. It's Mrs. Power again. It's really nice to be back with you. So at the end of the last session, I asked you if you could play a game of pairs, do you remember what you had to pick up? That's right. You had to find two numbers that went together to make 10. So your example on the sheet there was eight and two, I wonder what other pairs you found? Did you find five and five? Excellent. Nine and one or one and nine. Great. Three and seven. You did, well done. And four and six. Excellent. Well done. So we're going to carry on looking at number bonds to 10. On the next slide there's going to be an expression, and I want you to put your thumbs up, if you think it sums to 10, if you think the two numbers add together to make 10. Or I want you to put your thumbs down, if you don't think they add to 10, are we ready? One add nine. Does it sum to 10? Thumbs up or thumbs down? Good. Well done. One add nine is equal to 10. Excellent. Okay. Now what have we got? We've got nine add one. Thumbs up or thumbs down. Of course, it's thumbs up. Well done. Because when we changed the order of the addends, the sum remains the same. Well done. It equals 10. Now we have eight add two. Do eight and two sum to 10? Well done. They do don't they? Should we just double-check? We've got five and three more so there is our eight and here are my two fingers down here that would sum to 10. Okay, next one. Seven add eight. Does it sum to 10? Thumbs up or thumbs down? Well done. It's far too big, isn't it? Seven add eight, far too big. What about seven add three then? Seven add three. If you're not sure you can always check on your fingers. Seven add three sums to 10. Well done. So what do we think about this one? Six add four. You getting good at this? Well done. It does sum to 10. And this one? Five add one. Course not it can't be 10, can it? Five add one. Well done if you got that right. So we're going to carry on looking at our numbers that sum to 10 and our expressions that don't sum to 10. Okay? But this time we're going to think a little bit more about why they might sum to 10 or why they might not sum to 10. Okay? So our first one that we're going to look at is here. Eight add two, now you might already know something about this. So if you can tell somebody in the room or just shout it out. What do you think? Eight add two, does it sum to 10? Yes, it does. We know our number bonds now quite well. And eight add two is 10. We could double-check on our fingers. We could have eight of our fingers up and here are my two more. That would make 10. Good. The next one we're going to look at now is seven add six. What do you think? Seven add six. Does it sum to 10? It doesn't, does it? Okay. Why not? We know that 10 is made of seven and three. So six is too big, isn't it? It can't make 10 if seven add three makes 10. Okay, good. Right? Our next one we're going to... I think you're going to be good at this one. Five add five. I think because we're getting more familiar with our number bonds to 10, you probably know now that five add five is equal to 10. Five add five is equal to 10. Well done. Okay. The next one we're going to look at is four add four. Now the one before was five add five and we said it did sum to 10. So can four add four also sum to 10? You're absolutely right. No, it cannot. It does not sum to 10. Okay. Oh, I like this one. Right. One add zero. I think I could just shove the two digit together and that would be 10, wouldn't it? I just take the add out and shove the one and the zero together to make 10. No. Why doesn't that make 10? Oh, because if I have one and I add nothing to it, it's going to be one still, isn't it? Good. Well spotted everyone. What about this one? Zero add 10. Zero add 10. We're not trying to trick you. You're absolutely right. If I have 10 and I add zero to it, it's going to sum to 10, isn't it? Excellent. Well done. Okay. So what about this one down here? Six add five. What do we already know about our number bonds to 10? What have we already found out? Let's have a look. So five add five was 10. So can six add five, be 10? No, it can't. You might also know that 10 is made of six and four. Four and six. Okay. Well done. And the last one have you spotted anything similar to this one? Maybe you spotted, oh, look. We've already said that 10 is made of eight and two. So can 10 be made of eight and one? No, it cannot. Well done everyone. Right. Now we're going to have a think about whether our number sentences, our expressions are greater than 10 or less than 10. And we're going to borrow, got Blockzilla to help us with this. To help remind us what these symbols mean and how we use them. Okay. You ready? So here's Blockzilla. Can you see him there? And his mouth is one of our symbols. Do you think that this symbol is greater than, or less than. Have a look at the tree. The size of the tree is greater than the size of the flower. So when the wide end is at the beginning, we say that this is greater than whatever's on this side. This symbol is our greater than. Here's Blockzilla again to help us. And we can see now that he's facing the other way. So our symbol now has turned around and it is facing this way. And you see that number one is in there. And number three is that the wider end. This is because when the symbol is facing that way, it means, less than. Because one is less than three. The little end is pointing at the one. The lower number comes first. One is less than three. So which way is he facing now? Can you see? What symbol have we got here? Is it greater than, or less than? If you look at the numbers at the top of the slide, you might also get a clue. Three is greater than two. Well done. The wide end is open first. It's the greater end that's open first. So we say that three is this greater than two. Here we have our symbols and our numberblocks friends have come along to help us out. So our first symbol that we're going to look at is this one here. We're quite familiar with this, aren't we? What does it mean? This symbol here? It means equal to, doesn't it? Well done. This number here is equal to this number here and they fit nicely within the lines. Two is equal to two. Brilliant. Okay. Let's have a look at this one over here then. What about this symbol? Can you remember what we've already looked at? How would you compare one and three? The one is first. One is less than three. Good. Can you see the smaller end of the symbol is at the beginning. So one is less than three. There you go. Well done. And what about this one over here then? What must this one be? Which end have we got first? The wider end. So we say that three is greater than one. Well done everyone. We're going to use those symbols now. So now we're going to resort our expressions into whether they are equal to 10 or if they don't sum to 10, if they are not equal to 10, whether they are, did you say it? Less than 10 or greater than 10. Okay. So that's what we're going to sort through now. Now, if all of these expressions on this side, sum to 10, then which bits are they going to move into here? Which bit of the table? Should we find out? You're absolutely right. Well done. If they sum to 10, then that means that they are equal to 10. Well done. They are. Okay. So let's have a look our first here. We've already said it doesn't sum to 10. One add zero. Is it more than... is it sorry. Is it less than 10 or is it greater than 10? Well, one add zero, we know pretty quickly is going to be less than 10. Isn't it? Because it's just one. Okay. Let's have a look at our next one. Our next one is seven add six. And we've said it does not sum to 10. Can you remember why we said it doesn't sum to 10? We said that 10 is made of seven and three. But six is more than three, isn't it? It's greater than three. So when they sum together, it's going to be greater than 10. You're absolutely right. Well done. Now, can you remember what we said about this? We looked at our five add five, but this is only four add four. Well, four is less than five, so that must mean that four add four is less than 10. Well done everyone. Okay. Six add five. What do we know? Just talked about five add five. Haven't we? What's different here? There's one of the fives is the same, but what about this number here? This number is greater than five. So our whole number, our whole is going to be greater than 10. Well done everybody. Okay. Last one. Eight add one. Do you remember what we said? Eight add two is equal to 10. So eight add one must be less than 10. Why? Because one is less than two. For today's practise activity, I would like you to find three pots or cups or boxes, anything really, that you can put things in and I'd like you to mark them up with equal to 10, less than 10, and greater than 10. Well done. Then you're going to write out the three expressions that are on the screen, and you're going to put them in the correct pot. If there's somebody there for you to explain why you're doing that, that would be brilliant. If not, you can explain it to your teddy or something like that. Okay? Once you've done that, I then want you to write your own expressions. You can make them up and I want you to put them in the correct pot. Can you fill up each pot? Can you write enough expressions that are correct and put them in the correct pot? Maybe try them out with somebody else in your house, if you've got a brother or sister or a parent or any adult that's with you in the house or again, you could explain it to your teddy. I'm sure they'd want to know. Okay? Don't forget, the important bit is the explaining how you know which part it goes into. Have fun everyone.

Lesson summary: Reasoning with number bonds

In this lesson we reason about expressions using number bonds to 10.

Maths

Y1 Maths

Key Stage 1

Year 1

Reasoning with number bonds

Addition and subtraction

UNIT

The commutative Law of Addition using aggregation

The commutative Law of Addition using augmentation

Measures Contexts to Show the Commutative Law of Addition

Embedding Understanding of Equivalent Expressions

Ten can be partitioned into pairs of numbers that sum to ten

Numbers that Sum to 10

Adding one

Subtracting one

Consecutive numbers

Adding two

Subtracting two

Adding and subtracting with 5 and 3 and with 6 and 3

Adding or subtracting Zero

Subtracting a number from itself

Reasoning with number bonds

Video

Lesson summary: Reasoning with number bonds

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