Choosing calculation strategies to solve calculations

Key Stage 1

Maths

Exploring calculation strategies within 20

Which equations match the part, whole models.

﻿Hello mathematicians, it's me, Ms. Charleton and my talk partner Hedwig, and we are ready for some more exciting learning with you today. Have you got your talk partner ready? I hope so. Now today's lesson is exciting and also challenging. You've got to do a lot of mathematical thinking. So let's get started! Today's lesson, we're going to choose calculation strategies to solve different calculations. So you get to think about all of the strategies that you've learned or that you know about and choose the one that you want to use. You'll use a variety of different strategies, and then we'll be able to identify to find out which one is the best to use for different equations. Then you'll do your independent task and an end of lesson quiz. Today you're going to need a pencil, paper, and probably a whole part model, but don't worry if you haven't got one, you can draw one out. And let's have a think for a start. What could we use to help us add and subtract if we needed to to, what are those pictures showing? Can you have a little think? Hmm, I can see a bead string, can you spot the bead string? I can spot some dienes can you see those dienes? You might have used those in school. I can see some cubes, and I can also see something called Cuisenaire rods. You might have used those, and all of those can be used for counting to add and subtract, but obviously you could also use things like raisins and nuts and pieces of pasta and the things that we've been using in different lessons. So now let's have a think. Which strategies do you know? So those are the things that could help us add up, but we've also learned some different strategies. We've got the make 10 strategy, can everyone remember? We go make 10! Can everyone do that? Make 10! We could use number bonds, we could use a count on strategy. There are lots of other ones. We could also use near doubles. And those are the different strategies that we could use to help us solve equations. And those are the ones that are going to be thinking about today. So let's have a think, how would we calculate 3 + 9? What strategy could we use to solve that? We could use a number line to help us. Now I started at the number 9, because 9 is the biggest number, and it's much easier to start off counting with a bigger number and do fewer jumps to add on. If I did 3 + 9 and started at 3, I would have to add on all of those jumps. But instead I can start at 9 and add on 3. 9, 10, 11, 12, I'm counting on! I'm using the count on strategy, because 3 is a small number, so there are a small number of jumps that we could do. 3 + 9, use the count on strategy. We could also make ten! 9 is very close to 10. So if I made a group of 10 by adding one purple cube there, can you see that there are 9 turquoise cubes and then 1 more purple cube makes 10. And then we count on from there, a group of 10 and then 2 more, 10, 11, 12. There are two cubes outside that group of 10. Is counting on an efficient way to add 8 and 9? Think about what we just said. We could add on 3, because 3 is a small number, so there are only a few amount of jumps. But if I'm adding 8 and 9, there are a lot of jumps to go there, aren't there? We go 1, 2, 3, 4, 5, 6, 7, 8, and all the way up! But that means that if we do lots of jumps, there's more likelihood that we will make mistakes. So 8 plus 9, would we use a count on strategy? Can you show me if you agree, or if you disagree, if you think that there's a different strategy we could use. Well done, I think there's a different strategy as well. We could count on, but there are a lot of other ways that we could do it. Can you have a think about how you might do it? Hmm, maybe tell your talk partner. I told Hedwig that I might use the make 10 strategy, because 9 is very close to 10. Maybe you use that strategy, or maybe you thought of a different one. Maybe you could shout your strategy at the screen to me, could you do that? Great, I can hear lots of different ideas. Could I use the make 10 strategy to calculate 12 and 7? Hmm, let's have a think. I know I need to make 10, but could I make 10 with that one? Well 12 is already bigger than 10, so would I use make ten to do that? I disagree, I don't think I would, but there are lots of other strategies that you could use to count on for that one. This little boy says for 5 + 7 he's going to use the make 10 strategy. Do you agree with him that that would be a good strategy to use, or do you disagree with him? Would you use a different strategy? Have a little think now. You can pause the video if you want to, or you can tell your talk partner. Have a think, would make 10 be a good strategy for this equation, 5 + 7, hmm. I think, yes, that that would be a good strategy. Did you agree or did you disagree? I think make 10 would be a good strategy, because I know that 5 + 5 = 10, and I can partition that number 7 into 5 and 2. So 5 + 5 is 10 and 2 more. So the make 10 strategy would have been a good one here. What about 8 + 4? This little girl says I'll count on 4 from 8. Do you agree that count on would be a good strategy here? Or do you disagree, would you use a different strategy? Let's have a think, hmm. Well, I do agree with her that I think count on would be a good strategy, because 4 is a small number. So there's not many jumps, so I could do 8, 9, 10, 11, 12. But I also know that 8 is very close to 10, and I know that the number 4 can be partitioned into 2 and 2. Look, 8 + 2, oh that's a bond! I can use a number bond to 10. 8 + 2 = 10 and 2 more is 12! That was simple, wasn't it? So there's less likelihood that I could make a mistake there. So for 8 + 4, I'll use my knowledge of number bonds to be able to add that together. So as you can see, there are lots of different ways of solving a strategy, solving an equation using a different strategy, but some strategies are better for some equations because they are more efficient. That means they are quicker and it's less likely you'll make a mistake. Now it's your turn to explore. You need to have a little think about this equation, 7 + 8. This little boy says, "I'm going to use the near doubles strategy." I want you to have a think if you agree with him or if you disagree. Maybe you could use that strategy. Maybe you could think of other ways to solve that equation as well. So you can explore by just thinking about it, or you could write it down on a piece of paper and see how many different ways you could find to solve that strategy, solves that equation. Then you've got another one here, 12 + 6. This little girl says, "I'll use number bonds." 2 + 6 = 8. Would you use that strategy as well? Or is there a different strategy you could use? Pause the video now, there are different worksheets. Have a go at those and then we'll come back and we'll check them together. How did everybody get on? So this little boy said for 7 + 8 he was going to use near doubles. Well, I agree with him, because I know that 7 + 7, double 7, is equal to 14, and then there's just one more to equal 15, because 7 + 8, 1 more than 7, is equal to 8. And that's the same as saying 7 + 8 = 15. So you might have used that strategy. You might also have used a different strategy. You could've used the make 10 strategy or the number bond strategy. This one here, 12 + 6, she's going to use number bonds. She knows that 2 + 6 = 8, which is equal to 8 + 10. 8 + 10 = 18, so 12 + 6 = 18 and 8 + 10 = 18. She's used her number bonds, her knowledge of adding ones together to solve the equation. You've done a really fantastic job today, everybody. There are so many different ways to solve mathematical equations using different strategies, and it's quite challenging to think of them all. But the more practise you have, the more easily it will pop into your head. Should we tell Hedwig what she missed in today's lesson? Wakey wakey, Hedwig, wakey wakey! Now what did we do today? Well, we recapped the different ways of helping us solve some addition and subtraction equations. So we thought about using cubes and dienes and Cuisenaire rods. We also thought that we could use raisins and nuts and things like that, but today's lesson we solved the equations mentally in our heads using different strategies. For example, make 10, near doubles, we remembered that we could partition numbers. We used the number bonds, all of those different ways to solve different equations. And that helped us solve them really quickly and speedily and efficiently. Do you think you'd be able to do that? She's a little bit nervous about that today, and I think, do you know what Hedwig, that's so brave of you to tell everybody that you were feeling a bit nervous about using those different strategies. So that's great! So what you and I can do is that after this lesson, we can go and do some more practise. We can recap all those different ways. Maybe it's that you find it more difficult to do the make 10 strategy. Maybe you find it more difficult to partition a number, or maybe you find it difficult to count on and hold number in your head. But that's what's so good about practising . Thank you for being so brave. Are you excited about trying a different strategy now with me and practising it? She is, she's really excited about practising , because sometimes it can be really, really tricky. And it's good to be able to say, "I'm finding this hard, but I'm going to still keep practising ." And that's what Hedwig is really, really good at. Maybe you are too. Well done for today's lesson, everybody. You did a fantastic job. You can go on to your quiz and then do as much practise as you'd like. See you very soon. Bye bye!

Choosing calculation strategies to solve calculations

Choosing calculation strategies to solve calculations

Slide deck

Lesson details

Key learning points

Licence

Video

Worksheet

Starter quiz

3 Questions

Exit quiz

3 Questions

Lesson appears in

UnitMaths / Exploring calculation strategies within 20

Maths