﻿- Hi there, my name is Miss Darwish and for our maths assistance today, we are going to be looking at negative numbers. But before we get started, if I could just ask you to take yourself away from any distractions to a nice quiet place ready for the lesson. Okay, first of all, we're going to be looking at some negative numbers and then moving on to look at number lines and then worded problems. At the end of today's session, there will be a quiz then for you to complete. Okay, so if I could just ask you to get yourself a pencil or a pen, a sheet of paper or a notebook is fine, and a ruler. So if you want to grab these things, and then we can start the lesson. Okay, ready to start? Okay, negative numbers. So in front of us, I want you to read that number out for me. Can't hear you louder. Really loud. Okay. We can say, minus three, or what else can we call it? Negative three. So we can say it's negative three or minus three. Okay. Now negative numbers. Let's have a look at five take away three. Now, when we have a calculation, any calculation, this is just one example of a calculation. Every number carries a sign in front of it, okay? So that's three there, what's the sign in front of it? Negative or minus. Good. And what about the five? It's positive. But when it's at the front of the calculation, we wouldn't write plus five minus three would we? However, if it was minus three plus five, we would because it came after, but if it's at the start, if the numbers at the start and it carries a positive sign, or plus sign, then we wouldn't really necessarily write it. So that five carries a, it's a positive five, and the three is a negative three. Okay. What about minus seven plus eight? We've got a negative seven, and we've got a positive eight. And if I wanted to rewrite that, I could write eight minus seven, because by writing eight minus seven, I haven't changed the signs at all, have I? The eight is still a positive eight, and the seven is still a negative seven, and eight minus seven, is the same as five minus three could also be written as minus three plus five. Do you see that? Okay, let's recap again. So five minus three could also be written as, minus three plus five. So I'm just moving around the numbers without of course, changing the sign in front. So then minus seven plus eight could be the same as, or is the same as eight minus seven. So we're not changing the calculation to the calculation, the answers are still exactly the same. We are just moving the numbers around obviously with the sign, we can't leave the sign behind. Okay. And then minus four minus three? The four is obviously negative, the three is obviously negative. If I move it around minus four minus three could be? Minus three minus four. Again, we haven't changed anything around. Okay. And then four plus five? The four is a positive number, and the five is also a positive number. And we can write that as? we could also write it as five plus four. So again, I haven't changed the positive or the negative sign in front, I haven't changed the sign. Okay, so minus four. If this is the answer, what is the question? If the answer to a question is minus four, what is the question? What could it be? Have a think. You want to just jot down as many different questions as you could think of. I've given you the answer. You now got to write down some questions. Okay, should we have a look together? So it could be six minus ten. Let's check. We start at six. Start at six, and then we count minus ten. One, two, three, four, five, six, seven, eight, nine, ten. Ten less than six is equal to minus four. Did you have that one? Okay, there are other possibilities, of course as well. We could have five minus nine. So we start at the five and then key take away nine. So we've got, four, three, two, one, zero, minus one, minus two, minus three, minus four. The answer is also minus four. There are lots of different possibilities. Let's have a look at another one. Minus four is the answer, and the question could also be four minus eight. So we start at four there. And then we take away eight, three, two, one, zero, minus one, minus two, minus three, minus four. And then again, we could have minus three take away one, which would be equal to minus four. Did you have any of these? Okay, lets have a look at this question. Which one doesn't belong. So we've got seven minus eight, minus four minus three, six minus seven, and zero minus one. Which one doesn't belong? Or which one might be the odd one out? I'll give you a few seconds to have a look. If you want to make notes feel free. Should we have a look together? Okay, so seven minus eight is equal to? What do you think? Minus one. Minus four minus three is equal to? If I start at minus four, and then I take another three away, that'll be minus seven. So the first answer is minus one, the next answer is minus seven. Lets have a look at six take away seven, will be minus one. And zero minus one? Minus one. So which one does not belong? Minus four minus three, because it gives us an answer of minus seven. But The other three calculations give an answer of minus one Well done. Okay, let's have a look at some worded problems now. We're going to be calculating the goal difference. So we've got four teams. Brazil, Denmark, Iraq and South Africa. Now you can see the goals for, the goals against, and then the goal difference, GD goal difference. How has the goal difference been worked out for Brazil? They've taken the goals for, in this case in Brazil's cases it's four, and they've taken it away from goals against. Four take away zero is equal to four. Okay lets have a look at the rest of the table. So we got Denmark, Iraq and South Africa now. So Denmark, goals for one, goals against four. Remind me how do we calculate the goal difference? For minus against. goals for minus goals against so, one minus four is equal to? Tell me shout it to me one minus four is equal to? Minus three goals I hope you said that. Okay so have a look at Iraq now. Ooh bit different now. They've calculated the goal difference. They've told us the goals for, say how many goals against? One minus a number is equal to zero. While minus one of course is equal to zero . Well done if you said that. And then the last one South Africa. You ready? so again they've given us the goal difference and this time they've given us how many goals against two goals against. But goals for we don't know. So remember how do we work out the goal difference? Goals for minus goals against, is the difference between the goals for and the goals against. So a number take away two is equal to minus one. What do you think? I'll give you five seconds Four, three, two, one, show reveal. One One take away two is equal to minus one of course. Well done. Okay, let's have a look at some golf now. So we've gone from football to golf, still with the sport thing. Okay, so we've had a look at calculating the goal difference. Now we're going to have a look at something to do with golf. So this is about Justin Rose from Great Britain. And there are four rounds. Now, the Olympic golf course this one has a par of 71. Okay. Now in round one, Justin, what did he score? 67. Can you see that in the table? So we're just going to focus on round one. He scored 67. So Justin Rose scored in round one 67. But this Olympic golf course has a par of 71. So how many points away is 67 from 71. Can you work that out for me? Well done if you said four. 68, 69 70, 71. he's four away from 71 so that means for round one, he would have scored minus four. Does that make sense? So we see what he's scored in the round, and we see the difference from 71, and then based on that, that will give us a score, and then we add all the rounds together. Okay? Let's have a look at round two 69. Justin Rose in round two he got 69. So what does that give him a score of in round two? How far away is that from 71? Minus two. 70, 71. Okay. So round one, he scored a total of minus four, in round two minus two. Let's have a look at round three now. 65 this time. You're going to work out. Five seconds. Okay, should we see what you scored in round three, what do you think? Minus six. Add then round four. 67. Again, that will be nice and easy because it's similar to round one. So do a bit of cheating there. Say 67 away from 71. 68, 69, 70, 71. Four away so of course it'll be minus four. Now remember how did I say to work out the score at the end? His total score, he's finished his four rounds now. We just add up all the total. So minus four, minus two, minus six, minus four, and that will give us the final score at the end. Okay, so let's have a look. So from round one, he scored minus four. So we're starting at minus four. Can you see that? Okay, second round, he scored? Do you remember? Minus two. So we're taking away two. Third round what did he score? Do you remember? Minus six. So we started at minus four, we took away two we're at minus six, and then we took away six, and we're at minus 12. And then round four, it's the same as round one, wasn't it? So minus 12 we take away four, we are at minus 16. So his score was minus 16. Okay, well done. Now it's time for you to pause the video and have a look at the independent tasks that I have left you with. Good luck with it. Come back when you finish and we'll go through the answers together. Okay, welcome back. Hope you found that Okay, let's have a look at the answers together. So this is the task that I left you with. Complete the table below, showing the goal difference for women's football. So women's international football this time. So we've got four teams, Brazil, Canada, Japan and Zimbabwe. And we don't have the goal difference for Brazil, but we do have the goal difference for Canada, Japan and Zimbabwe, but it's different things that we've got to work out. So how did I say we work out the goal difference? For take way against the difference between goals for and goals against. So Brazil seven take away one is equal to? Six. Well done if you said that give it a tick. What about Canada? So we've got a number take away two is equal to minus one. Must be one. Well done . Give that a tick if you got that right. What about Japan? Five take way a number is minus one. Goals against, six. Well done. Five take by six is equal to minus one. And then the last one Zimbabwe. So three take away and number is equal to minus four. Seven. Well done if you said that. Okay just check through your table and compare it. Okay, hopefully you got that right. If you didn't, then it's okay to make some corrections. Okay, if you would like to share your work with us here at Oak National, then please do ask your parent or carer to share your work for you on Twitter, tagging @OakNnational and to use the #LearnwithOak. Now I just want to say well done on all the brilliant learning that you have to completed today on negative numbers. Now before I leave here, I'm just going to ask you to go and complete today's quiz. Good luck.

Quiz involving calculating intervals across zero.

Which of the below gives an answer of -1?

Which of the calculations below has the smallest answer?

A school football team scored a total of 3 goals in their recent games but let in 5. What is their goal difference?

I am in an elevator (lift) and I'm currently on level 6 but I need to get to -2. How many floors away is -2 from me?

The Olympic golf course in Rio has a par of 71 (expected number of strokes needed), if David scores 65, 70 and 66 on his 3 rounds, what is his total score?

Calculating intervals across zero

In this lesson, we will investigate and model problems involving negative numbers.

Maths

Y5 Maths

Key Stage 2

Year 5

Miss

Problem solving with whole numbers and decimals

Number

THEME

UNIT

Solving problems involving division with remainders (Part 1)

Solving problems involving division with remainders (Part 2)

Calculating and interpreting the mean as an average

Developing strategies to plan and solve problems

Adding 2 or more numbers mentally

Calculating across zero

Investigating properties of number

Exploring properties of palindromic numbers

Exploring properties of number

Which of the below gives the answer for 8 ÷ 5 ?

Which of the calculations below does not have any remainders or decimals?

From the set of numbers below which does not have a mean of 8?

Tickets to the cinema cost £8 each. Five friends go and each friend has the following amount of money: £9,£11,£6,£7,£6 Do they have enough money between them to pay for 5 tickets?

What is the answer to 87 - 88 + 89

Which of the following numbers is not a multiple of 11?

Which of the following numbers is not a multiple of 9?

Lesson overview:Calculating intervals across zero

Core Content

Problem solving with whole numbers and decimals: