Using ten times greater for known times tables

Key Stage 2

Maths

Multiplication and division

Which times-table can we double to find our 12s?

﻿Hello there everyone, I'm Miss Brinkworth. I'm going to be going through this maths lesson with you today, shall we look at our learning objective? What we're going to be doing, is we're going to be using 10 times greater for known times tables. So we're going to be using the timetables that you feel quite confident with, focusing a lot on our threes and our fours. And we're going to look at ways in which we can amend those to apply them to bigger, larger numbers. So we're going to be using lots of the things you're already feeling really confident with, but finding ways of applying those to new questions and new contexts. So, let's look at the agenda for today's lesson. So what we're going to be looking at today, is we are going to be recapping on three and four times tables like I said, they are one that you should feel quite confident with at the moment, so that's going to be the start of our knowledge, and then we're going to use that to apply it into new problems. We are going to explore the 10 times tables, and we're then going to move on to multiplying one digit numbers by multiples of 10. And then there'll be that independent work and exit quiz at the end to see how well today's learning has gone in. So, all you will need essentially is a pen or pencil and some paper, you definitely need that. What would be quite useful is some online diennes, so if you can ask a parents or carer to help you find some online diennes that would be really, really useful. Diennes are the little different shapes and size blocks that we use, when we're talking about place value. If you can't find those please don't worry, I will put images on the board as well. So, pause the video here and find your equipment please. Okay well done, let's get started. So, what I would like you to do, is match up the question and the answer. Now the questions were all worded slightly differently, but they are multiplication and division, multiplication or division questions. So pause the video and see if you can match up the question with the answer. Well done, really good try everybody. This is just a way of making sure that we recognise the language around multiplication and division. It's not always nicely written out with a division sign and a multiplication sign. Sometimes these are word problems or things that people are just saying to us in real life. So it's really important to recognise when, what we're being asked, it needs us to use our multiplication knowledge. So six groups of four, six groups of four, we know that multiplication is groups of things, so six groups of four is six times by four. Six times by four, how did you work out six times by four? Did you do two times by six and then double it? Or did you do three times by four and double it? Either way, hopefully you got the right answer, 24. 21 shared between seven people. Well we know that division is about sharing, so that question is 21 divided by seven. 21 divided by seven is three. Three lots of seven give us 21, really well done everybody. Eight equal piles of four, so we've got four somethings in eight piles. So we've got eight lots of four. We've got eight times by four, and again, for your fours, you could think about four times by four and double it, and you should get the answer, 32, well done. 25 split equally into five groups, well again we're talking about splitting, sharing, it's division. 25 divided by five is five, well done if you saw that. And then the last one matches here but let's just check that that answer does sound right. Nine lots of two, nine times by two gives us 18. Really well done if you've got all those questions right, you clearly understand the vocabulary that's used around multiplying and dividing, so it's going to really help you with today's lesson. Okay, so here we have a picture of some tiny baby moles, look how small they are, they're in somebody's hand, all those tiny little moles. And this question says, when baby moles are born they're usually two centimetres long. Adults are 10 times longer, how long is an adult mole? Well, pictures really help us, when we see questions like this. So let's have a look at what we can think of in terms of representing this question. Baby moles are two centimetres long and adults are 10 times bigger, so what is this question asking us to do? Well, there's another way of representing it, we've got a mole, an adult mole, and it's the same length as 10 little, baby moles. Don't be confused when you see pictures like this, an adult mole isn't made up of 10 baby moles, it's just the length we're talking about, it's got the same length as 10 baby moles. What does that picture look like to you? Well we're starting to get towards a bar model aren't we? So if we move on again, and we can think about changing that picture into a bar model. So that we've got the length of the adult mole is that whole bar, and then we've got the length of each mole is along the bottom in parts. What else do we know though? So here this bar model is still showing us a lot of unknowns we've got the whole is unknown, we've got 10 equal parts, but we haven't filled in everything we know yet. That's because we do know the length of a baby mole, we're told it in the question, we're told that the length of a baby mole is two centimetres and we know that the adult mole is 10 times that big. So, we can do two centimetres, and we can times that by 10. That gives us 20. So, times thing something by 10, we make it 10 times bigger, and you can see that two times by 10 gives us 20, we've still got the two going on there and we still got the two in our answers, but it's been made 10 times bigger. So two made 10 times bigger, gives us 20. Okay, let's have a think about that question in a slightly different way, a slightly different way of drawing out that question. We had fun with our pictures of moles, but what if we're going to use our dienes to represent this? So we could think of our two centimetres for our baby mole as two one diene blocks, so we've got two ones there. And we need to make them 10 times bigger, so for each one, we get 10. So, here's our adult mole, and hopefully this makes it clear that when we have two multiplied by 10, we've got 20. Our two individual blocks, one and two, have turned into two tens, 10, 20. Okay, let's try that again with a different question. I have collected three house points but my friend collected 10 times as many as me, how many does she have? Well let's have a go at representing this with our dienes again, here's my house points, my three house points. Sorry, I'll put those on as well. My three house points are represented with the three one dienes, my friends house points are represented in tens because she's got 10 times as many as me. What is the answer to three times 10? I've made three 10 times bigger, how many tens have I got, what's my answer? I've got three lots of 10, so I've got 30. Okay, here's your chance to have a go, I'll give you a chance to answer this question in your own way, if you've got online dienes please use them or you could draw them out, that's absolutely fine. Class A read four books, class B read 10 times this amount, how many dis class B read? So what's the question, how are you going to represent that? Well done, let's see how you got on. However you want to represent this question is completely up to you, as long as you get the right answer that's absolutely fine with me, and we all represent things in different ways, our minds work in different ways, and we do different working out which is all absolutely fine. Let me just show you what I did, I got my ones and my 10's, so I've got four ones, and then I've got four tens, because class A read four books, my four ones, but class B read 10 times as that amount, so for every book that class A read, class B read 10. So for every one, I've got 10. So four one's is four, four tens is 40. Whichever way you got to that answer, that's absolutely brilliant, well done. Okay, here's our 10 times table then, so, our 10 times table has got a very clear pattern, 10, 20, 30, 40, 50, 60. And some of you might be pretty confident with that 10 times table and that's brilliant, but I wonder if you've thought carefully about why it has that pattern. Let's have a little bit of a deeper look. So one goes to 10, I wonder why? Well here's your place value columns, just your hundreds, tens and ones. And what's happened when we multiplied by 10 is we've moved it one place value column, from our ones, into our tens, because we've multiplied it by 10. We've made it bigger by 10, by a factor of 10. So, one has moved from the ones column into the tens column and then we have that zero come in as that place holder. So one times by 10 is 10. Try that again with six turning into 60 when we multiply it by 10. It follows exactly the same pattern in our place value columns, six started in the ones, we times it by ten, we made it 10 times bigger, so it moved from the ones into the tens column. And that arrow there, it's just a really clear way of showing what we're doing when we're multiplying by 10. Often you hear, to multiply by 10 add a zero. That's not the right way to look at it, the right way to look at it, is that you are moving it one place value column, the zero is there as a place holder. Okay, have a go answering these multiplications of 10 and come back for the answers in just a moment, they should be quite simple for you. Great, so let's see how up to date you are with your 10's. Well done if you could see that what we do when we multiply five by 10, is the five moves from the ones into the 10's, and that zero comes in as the place holder to give us the answer 50, really, really good. Okay, let's move on then and apply this knowledge to slightly trickier questions. So what about six times 30? It's not 10 anymore, it's a multiple of 10. Six times 30, well, you know the answer to six times three, I'm hoping, you're really confident with your three times table, so six lots of three, what's six lots of three, shall we count? Three, six, nine, 12, 15, 18, is six lots of three. Okay, so what we're talking about six lots of 30. Well, three and 30 have that relationship with 30 is 10 times bigger than three. So we've made one of our factors 10 times bigger. So our answer is going to be 10 times bigger, so I can use 18, and I can make 18, 10 times bigger. Let's have a look at how we do that then. Here's 18, I've got a 10 and eight ones, I need to make both of those 10 times bigger. So my eight ones, goes to eight 10's, and my one 10 goes to 10 10's, which is a hundred. So 18 made 10 times bigger is 180 tens. 180, can you see the relationship between 18 and 180 is 10 times bigger? So, by using just my knowledge of my three tables and my knowledge about how multiples of 10 work, I can answer a question mentally, like six times 30. Isn't that wonderful? Okay, so here it is shown again, there's my 18 times 10, so I've made 18 10 times bigger to answer this question. And here it is in those place value columns, it's exactly the same as when we multiplied our one digit number by 10, but we've got two digits, they both move one place value column. So my eight has moved from my ones into my tens and my ones moved from my tens into my hundreds, again, I've got that zero as a placeholder, so 18 has become 180. Okay, your turn then, have a go at answering four times 50 and for a clue, use four times five. Well done, let's see how you got on. So, four times five is 20. So there's 20, and there's 20 made 10 times bigger, so each 10 turns into a hundred. So 20 made 10 times bigger is 200, so four times 50 is 200, well done if you could see that. And here it is again, just in those place value columns where you can see that we moved our zero into the tens column, our two into the hundreds, and we've got a zero there, in our ones, as a place holder. Okay, time for your independent task, take as long as you need and let's come back together and discuss the answers when you're ready. Well done for having to go at the independent task everybody let's see how you got on, So what you needed to do on part A, would answer the questions in the first column and use those to answer the questions in column B. Because those are multiples of 10, and you can use your knowledge from A, to answer B. So let's see how you got on. Two times by seven is 14, and you can make that 10 times bigger to answer 20 times by seven is 140. So this is that relationship that we're drawing here. Probably at the beginning of the lesson, a question like 20 times seven, was maybe not something you could answer, but now I'm hoping that you can use the times table knowledge that you already have, that's your two times table there, and apply those rules about making it 10 times bigger to answer questions that were maybe a bit trickier at the start of the lesson, Four times three is 12, and we can use that to answer four times 30 is 120. Eight times five is 40, so 80 times five, 40 made 10 times bigger, is 400. Nine, three times nine, 27, so made 10 times bigger, is 270, and four times four, the one I always make a mistake on, four times four is 16, got to remember that one, 16 gives us 160, really well done if you got all of those right everybody, you're getting really confident at using your timetable knowledge in new situations, really, really well done. Okay, hopefully you spotted these mistakes here on the working out that people have done. Now these are common mistakes that people make when they're getting this new skill about multiplying by 10. So, here they've got the numbers in slightly the wrong order so, six times by 30 should be 180 not 108, and if you think carefully about each digit, moving a place value column, hopefully you won't make that mistake. 90 times by four, I think somebody's got a bit happy adding zeros onto the end of their number here. The numbers only move one place value column, when we've made one of our factors 10 times bigger. That brings us onto the last mistake, 40 times by 40 is not 160, that's because both numbers have been made 10 times bigger, so the actual answer was 1600, don't worry if you didn't get that answer, 'cause we didn't cover that in today's lesson, but really well done if you could see that there was a mistake there, in that question. I'd love to see your working out for today, So if you'd like to, please do make sure you ask a parent or carer first, but you can share your work on Instagram, Facebook or Twitter, tagging @OakNational and #LearnWithOak. Now there's a quiz for you to have a go at just checking today's knowledge and seeing how many of those you can get right. You've worked fantastically well today everybody, well done, enjoy the rest of your day, bye, bye.

Using ten times greater for known times tables

Using ten times greater for known times tables

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UnitMaths / Multiplication and division

Maths