Lesson video

Hi, everybody.

Welcome to today's lesson.

I'm Mrs. Crane, and today, we're going to be rounding to the nearest 10.

How are you today? I hope you're well, and I hope you're ready to do some rounding.

In a moment, I will go through all of the equipment we will need for today's lesson, so don't worry about that just now.

If you can, can you turn off any notifications on your tablet, phone, or device, whatever device you're using for this lesson.

And then if you can find somewhere in your home that's nice and quiet, and distraction free, we'll be ready to start.

When you're ready, let's begin.

Okay then, let's talk through today's lesson agenda.

To begin with, we're going to be using a counting stick, then we're going to be exploring by picking a number, then we're going to be looking at rounding on number lines, and finally, your independent task today will be: can you round a number to the nearest 10? Then we'll go through the answers together.

So, let's get started.

To get started today, we are going to need a pencil and some paper.

Please pause your video now to go and get those things, if you haven't got them already.

Welcome back.

So, when do we need to round? I'm having a think.

I want you to have a think, too.

When in real life do we need to round? Okay, I can think of some ideas.

I sometimes get in the bus to places, and if I'm getting a bus, and the place I'd like to get to is, oh, I don't know, 32 miles away, I wouldn't say, "I'm going to get a bus journey that takes me 32 miles." I'd probably say, "My journey's going to take me 30 miles," and round it to the nearest 10.

Those of you that don't realise, chocolate is one of my favourite things.

And if I was going to buy a chocolate bar, and it was 97p, I would probably say, "It was a pound," and round my amount up, because 97 is pretty close to a pound, and I'll probably just pay the pound.

Finally, if I was going to walk down to the sea, I live near the sea, which is very lucky for me.

And it takes me about 12 minutes from my house, but I would probably say, "Oh, it's a 10 minute walk." And I probably wouldn't say, "It was a 12 minute walk." I would just round it to the nearest multiple of 10, and say it was 10 minutes, and it would take me about 10 minutes.

Can you think of any other examples that you use when you're talking about time, or money, or distances? I'm sure there's lots and lots of other ones too, but those are three that I could think of when we round in real life.

Now, today, we're going to be rounding some numbers.

And to be able to do that, we need to do two things.

Firstly, we need to be able to identify the nearest multiples of 10.

Then, once we've done that, we need to know where our number falls, to be able to know where our number needs to round to.

Does it need to round up, or does it need to round down? Okay? So for the first number, the first number is 56.

We need to identify the two nearest multiples of 10.

Now, I know that 56 sits between 50 and 60.

If you were in a real classroom, I would probably get my counting stick out, hold it up here, and be showing you on my counting stick.

Instead, we're going to today.

So all you need to do is use this, and look at this when I'm talking to help you today.

Okay? So we're putting 50 on this end, and 60 on this end.

Now, we can answer the first part, because we know that the nearest multiples of 10 are 50 and 60.

My number 56 sits in this area somewhere.

Now, how do I work out where 56 sits on my counting stick? We can count.

So, together with me: 51, 52, 53, 54, 55, 56.

And there it is.

Okay? Now, once I've done that, I know where it is.

I still don't know which multiple of 10 it rounds to.

How can I work that out? Well, I've put in a green line here, and if I had a real counting stick, I would be showing you that on my real counting stick.

That counting stick line has been placed exactly halfway between 50 and 60 for a reason.

Because if when we're rounding to the nearest multiple of 10, which we are today, the number in our one's column is 4 or less, it rounds down to the lower multiple of 10, which is 50.

If the number in our one's column is 5 or more, it rounds up to our nearest multiple of 10, which is 60 today.

Okay? So imagine that as our halfway kind of cut off point.

If it's 4 or less, we round it down.

Today we're looking in our one's column.

If it's 5 or more, we round it up.

We can clearly see that 56 is actually closer to 60.

We can see that, so we don't even need to really worry too much about this here, because we know that it's closer to 60, so it rounds to 60.

It rounds up.

So 56 is rounded to the nearest 10, is 60.

Let's have a look at a few more examples before we have a go at doing anything independently today.

Oh, we can have it shown like this here.

This symbol here just tells us that it's approximate.

It doesn't mean that it's exactly, it's not equal to.

So 56 isn't equal to 60, but when we round it, it's closer to 60.

Don't need to worry too much about that today, it's just there to show you.

Okay? Now, next number we have is 724.

This time, we've got a three digit number.

Doesn't make any difference.

We still need to identify which are the two nearest multiples of 10? Okay? This time, my two nearest multiples of 10 are three digit numbers, because the number 724 is a three digit number.

So, 720 is one of them, and 730, well done.

Now, what was the next thing that I needed to do? Oh, I can fill it in to my sentence first.

The nearest multiples of 10 are 720 and 730.

Now, what must I do next? Yes, that's right, I must mark on 724.

To do that, let's count on our stick.

721, 722, 723, 724.

I'm going to mark on where that.

oh I'm not today.

Not going to mark it on.

You, if you want to, can imagine, and I can mark it on virtually with my pointer here, that this would be our halfway point.

But we know, if it ends in a 4, and it's not past our halfway point, which is the 5 here, 725 here, then it rounds down to 720.

So I can say 724 rounded to the nearest 10 is 720.

Again, we can show it like this here.

This time, my number is a four digit number.

I still need to identify those two multiples of 10 first.

So, let's find out what the nearest multiples of 10 are.

I know here on my counting stick, I need to put 3,760.

And here, I need to put 3,770.

Those are the two nearest multiples of 10.

I then need to identify where my number is.

It's 3,764, so I can count 3,761, 3,762, 3,763, and 3,764.

Oh, I forgot to mark it up here.

We know those are the two nearest multiples of 10.

Here is our number now.

Now, we need to round it to the nearest 10.

It ends in a 4.

We're looking at the one's column, and it's a 4, so I need to round it down to 3,760.

We can clearly see it's closer to 3,760 than it is to 3,770.

Again, we can show it like this here.

This time, if you're feeling really confident, what I'd like you to do now is pause the video, and have a go at firstly identifying those two nearest multiples of 10.

So the numbers that go on this end and this end of our counting stick.

Then, I would like you to have a look at where our number falls between those two numbers on our counting stick.

And then, have a go at rounding it to the nearest 10.

If you're not feeling so confident, don't worry, we'll go through the example together now.

Okay? So, the two nearest multiples of 10 are going to be 7,830 and 7,840.

Both multiples of 10, both surround this number.

Now, to mark it on, I can see there's only a 1 in my one's column, so that's going to be quite straightforward.

I can mark it on here.

I got carried away again.

The two nearest multiples of 10 are 7,830 and 7,840.

Now, we can mark it on.

There it is.

7,831.

Now, if I want to round that to the nearest 10, which 10 does it round to? Does it round down to 7,830, or does it round up to 7,840? Absolutely, it rounds down.

We can clearly see that it's much much closer to 7,830 than it is to 7,840.

So we can say here, 7,831 rounded to the nearest 10 is 7,830.

Got my sevens and my eights all confused today.

I hope your brain's more switched on than mine.

Again, we can show it like this here.

Now, before we have a go at our Let's Explore today, I want to you to have a think about a question.

I have had a go at an example.

Have I done it correctly? So, I've said here, "3,455 rounded to the nearest 10 is 3,450." Yes, I've rounded correctly, or no, I haven't rounded it correctly.

If you would like to take a few minutes to work it out, pause the video now, and then I'll go through whether I have or haven't worked it out correctly in a moment.

Okay, let's work it out.

Have I correctly rounded this number or not? So, let's mark on those two multiples of 10.

3,455 sits between 3,450 and 3,460.

Now let's mark on 3,455.

Oh, absolutely bang in the middle.

Now, let's go back to what we discussed earlier.

If it's 4 or less in the one's column, we round it down.

If it's 5 or more in the one's column, we round it up.

In the one's column this time, it's a 5.

Although it's exactly halfway, because it's got a 5 in that one's column, we have to round it up to 3,460.

I've rounded it to 3,450.

Have I rounded it correctly? No, I haven't.

I've got a bit confused.

My answer should be 3,460.

No, I'm not correct this time.

So, let's have a look at today's Let's Explore, which is going to be pick a number.

Okay, on the grid here, you can see there are lots of different numbers for you to pick.

The bottom two rows here are the challenge rows.

So if you're feeling like you'd like a challenge today in our Let's Explore, pick one of these numbers.

You're not feeling like that, then pick one of the numbers from the first two rows.

You've got your counting stick here.

What I'd like you to do is mark on, so you might want to use your paper to do this.

The two nearest multiples of 10, mark on your number, and then decide whether your number rounds up or down.

Remember to look in the one's column to help you today.

Then what we'll do is discuss this together afterwards, predominantly going to discuss the challenge questions here.

So, when you're ready, give yourselves a go.

Okay, so I'm going to put myself back, so you can see me again.

Why were those questions, the bottom two rows, more challenging? What makes those numbers more challenging when we look at them? What do you think? Have a really careful look at the number that's in the one's column.

Or have a look at how many digits are in the number.

Have a really good look.

So, I'm going to talk through a couple of the examples.

Start with this number here.

1,465.

What made that more challenging? Well when I look at it, I can see there's a 5 in the one's column.

Now the 5, because it's halfway can get a bit confusing and tricky.

But if we think back to my example earlier, we knew that if it has a 5 in the one's column, we round it up.

So it's not as challenging as it looks.

The same goes for the number 7,455.

Again, ends with a 5 here.

We have to remember that 5 rounds up when 5 is in the one's column, and we're rounding to the nearest multiple of 10.

So again, it's not as challenging as it looks, but it could throw us.

Now, what do you notice about these two numbers here and here? Do you notice about those two numbers? 250 and 6,380.

Well what I notice about those two numbers is they both end in a 0.

Now, I know that 50 and 80, we look at the 10's in both of those, are both multiples of 10.

So when I'm rounding to the nearest multiple of 10, let's not get confused and throw ourselves.

250 doesn't need to be rounded, really.

So we can just say our nearest multiple of 10 is 250.

And same for 6,380.

It doesn't really need to be rounded.

It's already rounded to the nearest multiple of 10.

So if we've got that question, we can just write that number in again.

Because it is a multiple of 10.

Don't let them throw you, though.

Now, why is number 4 quite tricky? Why is number 4 quite tricky? Well, the number 4 is tricky because it's a one digit number so the two multiples of 10 that it sits between are 0 and 10.

So if we imagine those here, you have a 0 here, and 10 here.

Because there's a 4 in the one's column, we know it rounds down, and the number can round down to 0.

Okay? And the last one, 4,999.

Now, I find that tricky, because to identify the two nearest multiples of 10, here that's quite straightforward.

It's going to be 4,990.

But here, the nearest multiple of 10 is actually, quite a few of our digits are going to change, because it's going to be 5,000 here.

Because it ends in a 9, we know we need to round it up.

So numbers like that can get a bit tricky.

But we just need to keep thinking about what were those two multiples of 10 that our number sits between.

Okay? Okay then.

Now we're going to move on to looking at our numbers when they're on a number line, and not on a counting stick.

Now, a number line and a counting stick aren't that different.

But, often if you're given a question, they look quite different, and they can throw you a little bit.

So, a number line we can use in the same way, but we're going to use it slightly differently, because it doesn't show us the colours in the same way.

Okay? So, again, the first thing I'm going to do is mark on the two nearest multiples of 10 to the number 8,327.

So the nearest multiples of 10 are 8,320, and 8,330.

What's the next thing that I need to do? Well done.

I need to mark on this number onto my number line.

I can do that by counting until I get to 8,327.

I'm on 8,320, 8,321, 8,322, 8,323, 8,324, 8,325, 8,326, and 8,327.

Let's mark it on.

There we go.

Now, clearly, which end of our number line is it closer to? Well it's definitely closer to this end here.

So I know that it rounds to 8,330.

I also can see that there's a 7 in my one's column.

And I know that if it's a 7, it rounds up.

Next then.

7,455.

When I look at this, straight away I can see it ends in a 5.

So I need to be really careful when I'm rounding it.

Now the two nearest multiples of 10 that it sits between are going to be 7,450 and 7,460.

I know it goes exactly halfway, so I'm going to mark it on halfway.

Now I know if it ends in a 5 in the one's column, I need to round up.

So my answer is going to be 7,460.

And my last example.

If you're feeling confident, I would like you to have a go at doing this one before you hear my explanation.

If you're not feeling so confident, don't worry, we'll go through this last example together.

Okay? So again, first, I'm going to mark on my two nearest multiples of 10.

This time, they're going to be 6,890, and 6,900 is going to be the nearest multiple of 10.

Now, to mark on 6,898, I could count all the way up.

But I know that 8, in my one's, is 2 down from my 10 one's.

So I'm going to count backwards this time.

I'm going to mark it on here as 6,898.

That is the most efficient strategy I find when I'm marking on a number that I know ends in a 7, an 8 or a 9 usually.

Because it makes it quicker for me than counting up 1, 2, 3, 4, 5, 6, 7, 8, when I can count back 2 really quickly.

Because I know my number bonds to 10 pretty quickly.

Okay? So, now I know it's here.

Which number does it round to? Rounds up to 6,900.

So I can put my answer here.

Okay, for your independent task today, I would like you to have a go at this question.

Can you round a number to the nearest 10? So, going to hide myself for a moment so you can see what you need to do.

So keep listening, that's fine.

First, I would like you to locate the number on questions one and two.

You've already got the multiples of 10 in for you.

Then, I would like you to decide which is the nearer multiple of 10, and write in your answers here and here.

Questions three and four.

This time, you're going to need to mark on those nearest multiples of 10.

Then you need to locate that number.

And then you need to decide which is the nearest multiple of 10, and write in your answer, and the same for questions five and six.

I also have a challenge for you today.

My challenge is, I've rounded a number to the nearest 10, my answer is 2,830.

What could my number have been? Please pause the video now to complete your task.

Once you've finished, we'll go through the answers together, so don't forget to resume the video again.

Okay, welcome back.

You can see me again now.

So we'll go through these examples together.

First thing you needed to do on questions one and two, was locate the number.

Number was 78.

The number 78 goes here.

Does it round up or down? We know it rounds up, to the number 80.

322 then, it's marked here for the nearest multiples of 10 for you.

Need to mark on our number, which is here, 322.

Does it round up or down? Down, well done.

To 320.

Next then, three and four.

This time I needed to mark on closest multiples of 10.

So the number was 7,000.

7,000 is really coming up a lot today.

Don't know why I'm saying it so much.

It's not 7,000, because it's a three digit number.

It's 735.

730 goes here, 740 goes here.

735 goes exactly in the middle.

We know that there's a 5 in the one's column, so we know we need to round it up to 740.

Next one, then.

9,289.

Going to put 9,280 here, and 9,290 here.

Going to mark on my number 9,289.

Does it round up or down? Well done.

It rounds up to 9,290.

Questions five and six then.

1,119.

Going to mark on my two nearest multiples of 10.

1,110 and 1,120.

Let's mark on our number.

1,119.

Does it round up or down? Well done, it does, it rounds up to 1,120.

And my last number is 7,656.

Finally a 7,000.

My two nearest multiples of 10 are 7,650 and 7,660.

Let's mark on our number.

Then if we go, we can see it here.

Ends in a 6.

Does it round up or down? Fantastic, it rounds up to 7,660.

Now for my challenge.

I've rounded a number to the nearest 10, and my answer is 2,830.

What could my number have been? So let's have a look at how I worked it out.

Well, it could have been between 8,000.

I'm doing it again.

2,820 or 2,830.

But it could only have been any number between 2,825 and 2,830 here.

Because any number lower than that, so 2,824 or lower would round down.

So it could have been any of these following numbers: 2,825, 2,826, 2,827, 2,828, 2,829, or it could have been between the next two multiples of 10.

So here, we mark on 2,830 and 2,840.

And we mark on the halfway point.

It can't be this number.

It can't be 2,835, because it ends in a 5, so it rounds up.

But, it could have been any of these numbers here.

So it could have been 2,831, 2,832, 2,833, or 2,834.

So if you've got any of those numbers, then absolutely, you've worked out my challenge today.

Very impressed.

If you would like to, please ask your parent or carer to show your work from today on Twitter by tagging @OakNational and #LearnwithOak.

Well done for your really hard work today.

Brilliant rounding, and hopefully I'll see you again soon.

Thank you, and bye bye.