Lesson video

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Hi, it's Mr. Whitehead.

Sorry, I was a little bit late.

I was just closing the door because there's a bit of noise happening in the next room and I need to focus for the next 20 minutes on some maths learning, so I've shut the door to help me be ready.

If you need to do the same, then please do.

You can pause and then come back when you're settled in a quiet space ready to focus on your learning.

Press pause and come back when you're ready or let's get started.

In this lesson, we are rounding decimals with one decimal place to the nearest whole number.

Our agenda for the lesson, we're going to start off with some counting in multiples of 10, hundred and thousand.

Before we start looking at rounding whole numbers which we can follow up with looking at rounding decimal numbers.

There are connections between each of those steps that will help you with the learning in this lesson and we'll leave you ready for the independent task at the end.

Some things that you'll need.

So you know what to do, collect a pen or pencil, some paper and a ruler, press pause while you get them.

Come back when you're ready, and press play again.

Let's start off with the counting, then.

First of all, I would like you to count in multiples of 10.

So perhaps as you imagine, or if I hold a pen and let's imagine it's like a drum stick, every time I beat my imaginary drum, I'd like you to say the next multiple of 10.

So if we started from zero, 10, 20, carry on.

And stop.

Tell me the number that you got to.

Say it again.

Fantastic.

This time, let's start at 50 and continue beyond 100.

Ready? 50, 60, 70.

And stop.

Did you get 120? Good work, well done.

Let's have a think now about some multiples of hundred.

Same again.

Wait for that imaginary beat of my drum.

On three, one, two, three, 100, 200, 300.

Stop.

What did you get to? Good work.

And let's jump up now to multiples of thousand, ready.

One, two, three.

1,000, 2,000, 3,000, 4,000.

Stop.

Where did you get to? 8,000? Good work.

So a little bit of counting there in multiples of 10, hundred and thousand and using that language of multiples to help you with this first task.

I have four numbers and a table for you to fill in.

Now I asked you to get a ruler.

You don't need to use your ruler to copy out this table exactly as it looks, the lines are not necessary, the ruler is for later but do organise your thinking and your solutions so that you can easily group them.

Notice that first of all, I'd like you to round all of those numbers to the nearest 10.

Then I'd like you to round those same numbers but to the nearest hundred.

And then those same numbers again to the nearest thousand.

Press pause while you have a go.

Come back when you're ready to take a look at the solutions.

Press pause.

Are you ready? Let's take a look.

So rounding to the nearest 10, hold up your sheets.

Let me see how hard you've worked, first of all.

Good and I'm looking at firstly, just those rounded to the nearest 10.

Notice that I've coloured some of the digits in pink to draw your attention.

525 rounded to the nearest 10.

Is that going to be rounded to 520 or 530? I'm thinking about the nearest multiples of 10 the previous and the next.

Now we know the solution is 530.

With this number it's special, 525, five, what? 525 is halfway between 520 and 530.

We can't say it is closer to either of them.

Because of that, we just always say the next multiple.

Whenever there is a five involved and it's determining the rounding, we round to the next multiple of 10 or hundred, or whichever we are rounding with.

So these are the other solutions then.

1083 is nearer to 1080 than it is to 1090.

So we're thinking which of those closest multiples previous and next and then which of the two is the number closest to.

That's summarised there in this sentence.

Can you read that sentence aloud on three, one, two, three.

When rounding, consider, which is the of to that number? Good work.

Now we're thinking about the next column.

Notice that the coloured digits have changed when we round into the nearest hundred.

So this time that first number is 525 closest to 500 or 600 is closest to 500.

We're thinking about multiples of hundred and which our number is closest to.

Here's the sentence.

Let's read it together.

One, two, three, when rounding to the nearest hundred, you need to consider which is the closest multiple of hundred to that number.

Last column.

Wait for the digits to change.

So this time where those pink digits are, are the parts of the number that we are thinking about to help us decide the solution to the rounding to the nearest thousand.

So this time 525, it's either going to be closest to zero or thousand.

Which is it closest to? Closest to 1000.

1083, is it closest to 1000 or 2000? 1000.

Here are the other solutions.

And our sentence you say on your own this time.

One, two, three.

Well done.

Okay, so we've started our session by thinking about rounding to the nearest multiple of hundred, thousand, 10, but why do we round? And when do we use rounding? Maybe away from the classroom or away from our maths lessons.

Have a think.

There's a couple of sentence starters to help your thinking if you'd like to use them.

Press pause and come back when you're ready with some ideas why do we round or when do we round? Press pause.

Are you ready? So, any ideas when I'm shopping.

Did you have any examples? Here's one that I thought of for both of them, actually.

When I'm shopping, I might say that something which costs one pound 99 is about two pounds.

I've rounded to the next pound to the nearest pound, to help me talk about the cost and actually when I'm shopping and I am rounding often I will round to the next multiple of or the next whole number rather than the previous because I don't want to think that something's cheaper than it's actually going to be.

I'd rather think, oh, it's going to cost this amount.

And this amount is more than it really is.

So I'm going to get some change.

Or I know that when I pay it's actually going to be a little less.

How about when you're measuring my example, if I measured a pencil or pen, my drumstick, back to a pen, if I measured this, instead of saying, I mean that one maybe is 18.

7 centimetres.

Instead of that, I might say it's about 19 centimetres long.

Again, rounding to the next whole number to help me talk about its length.

So a couple of examples and maybe you had some different ones that you thought of for when you use rounding.

Let's start connecting this together now with our lesson's focus on rounding decimals with one decimal place.

We're going to be rounding those decimals to the nearest whole number.

Look at these three.

Which of them is a whole number? Which of them is not? Hmm.

Can you tell me one of those that is a whole number? Seven.

Can you tell me another one that's a whole number? No you can't, can you? Seven is the only whole number there.

The others that we've got, we've got decimals, we've got decimals, decimal tenths, and a fraction representing a number of tenths as well.

So we're thinking about whole numbers like that number seven, and our solutions will be whole number solutions after we've been rounding today.

Here's our first one then.

3 rounded to the nearest whole number is? Let me show you how I would think about this and I'll give you a go with the next one.

So I would be thinking, which is the previous whole number and which is the next whole number or I could think the previous multiple of one and the next multiple of one from 7.

So I've got seven and eight.

Then I'm thinking, well which of those two is 7.

3 closest to? It's closest to seven.

So 7.

3 rounded to the nearest whole number is seven.

Here's one for you to try.

23.

7 rounded to the nearest whole number is? If you do have a ruler have a go at drawing a line like my one here to represent your thinking and to support your explanation.

Press pause while you have a go at that.

Come back when you're ready.

Ready? So what did you get? On your number line, which is the previous whole number? And the next? Good 23 and 24.

So then we're plotting 23.

7 and it's closest to 24.

23.

7 rounded to the nearest whole number is 24.

Good.

Here's another one.

So have a think about whether you want to represent this with either of these two number lines both representing length divided into 10 equal parts and represent 5.

5 for me please.

Press pause, press play again when you're ready.

Are you ready? Okay, so which is the previous multiple of one? And the next multiple of one? Good and we can think about that as the previous whole number, the next whole number five and six.

So 5.

Mm.

Right in the middle.

Which of the two multiples of one is 5.

5 closest to? Is it closest to five or closer to six? It's halfway between, so again, a little bit like the example earlier.

In this case, we round to the next whole number, to the next multiple of six.

It's just a rule that we will always follow with rounding.

Say the sentence for me please in full.

5 rounded is? Good.

Well done six.

Okay, a task for you.

I would like you to pick a number from the grid.

For example, 2.

I then we'd like you to use this sentence and this sentence to help you explain which multiple of one 2.

3 would round to.

Which is the nearest whole number to 2.

3? So for example the first sentence, I'm rounding the number 2.

3, the nearest multiples of one are two and three.

The number is closer to two, therefore rounded to the nearest whole.

It is approximately equal to two.

Press pause, pick one, two, three different numbers of your own choice and have a go at saying both of those sentences to help explain your rounding.

Press pause, and then come back when you're ready.

How did you get on? Did you manage to use the sentences to help explain your rounding? Good work.

Maybe an example here, 70.

If I'm rounding that number, the nearest multiples of one are good, 70 and 71.

The number is closer to 70.

Now we haven't drawn a number line here but perhaps I know when maybe you are, I know I am visualising in my work using my working memory and visualising a number line and I can see 70 and 71.

And I'm thinking, where would 70.

4 be? And then which of those two is it closest to? So we can use drawn number lines and we can visualise them as well and therefore rounded to the nearest whole, it is approximately equal to 70.

6, just tell me the previous whole number and the next whole number.

Zero and one, good.

And tell me with this one which whole number it is closest to.

Nine, not eight, nine.

Even though it's halfway between the two of them we round to the next multiple of one, the next whole number.

Okay, another couple for you to look at.

So perhaps this time you will do some visualising instead of drawing the number lines.

If you would still like to draw a number line to help explain your reasoning, then that is fine too.

7 rounded to the nearest whole number is? Press pause, come back when you're ready.

Ready? And what is it nearest to? Good.

Let's have a think then.

Maybe you were visualising a number line with two and three and 2.

7 closest to three.

Now notice the symbol that I've used here.

7 is hm to three.

Have you seen this symbol before? I really like it because it's similar to the equal to symbol.

It's about the same as the equal to symbol but it is different.

And we call it the approximately equal to symbol.

7 is approximately equal to three.

7 is about three.

7 is approximately equal to three.

I quite like that symbol.

Although there are lots of words to say when you are naming it.

Here's another one.

So again, try visualising a number line in your mind to help you explain which whole number 72.

6 is closest to.

Press pause and come back when you're ready.

Ready? Tell me, if you visualise the number line, tell me the two numbers on either end.

72 and good 73.

Which of those two is it closest to? Let's have a look.

Closest to 73.

There we go again.

Can you say the sentence please that matches this and use the correct words for the symbol.

One, two, three.

72.

6 is approximately equal to 73.

Well done.

In a moment, I'm going to ask you to press pause because you are ready for the independent task.

There are six number lines empty right now with six decimal numbers that I would like you to round to the nearest whole.

Prove your answer on a number line.

So maybe visualise first but then prove what you've visualised by marking it onto a number line.

If you're ready for a challenge, finding all the possibilities, a number with one decimal place is rounded to the nearest whole number.

The answer is three.

What could the original number have been? How many possibilities are there? How do you know if you have found them all? Ready for a challenge? Give that a go as well.

Press pause, go and complete the activity, then come back and we'll look at the solutions.

How did you get on? Can you hold up your book for me? Let me take a look and let me see if you've used a ruler for those number lines.

Have you kept them neat? Have you tried to keep those spaces, those intervals equal? Good.

Let's take a look at the solutions.

Here are the first two.

So I'm visualising and I know that those arrows, the pink arrow, is representing the previous multiple of one.

The kind of bluey purply arrow is representing the next multiple of one.

And the green is representing the decimal number that I'm rounding.

I can see that green arrow is closer to the pink arrow.

92.

3 is closer to 92 and 0.

7 is closer to one.

So we've got approximately equal to as our symbol.

The next two, have a check.

How did you get on? 28 and three? And the last two.

How did you get on? Hold up your work, let me see if we've got some ticks or perhaps if we've got any that we've looked at again and if we're looking at them again because it wasn't right the first time, fantastic.

Because now there is even more learning as you work out where you went wrong you are learning something more, and that is brilliant.

That's why we're here, of course.

Now they're ready for the challenge.

I'm not going to go through because in the next lesson we are all going to try to solve problems, just like this using our knowledge of rounding.

So maybe keep that handy and bring it with you to the next lesson when we all have a chance to work on some of those problems. However, I will finish off with one last activity.

Approximately how tall are the animals? The something is something metres tall to the nearest metre.

There's our giraffe.

Can we say the sentence for the giraffe? One, two, three.

The giraffe is 5.

2 metres tall to the nearest metre.

Has Mr. Whitehead made a mistake? I need to round to the nearest metre.

Okay, let me try again.

The giraffe is five metres tall to the nearest metre.

Better? Good, how about the camel? One, two, three.

The camel is two metres tall to the nearest metre.

And the rhino one, two, three.

The rhino is two metres tall to the nearest metre.

No? Another mistake? Okay, help me out.

It's not two metres tall to the nearest metre.

4 I'm visualising it's closer to one, not to two.

So the rhino is one metres tall to the nearest metre.

Thanks for your help.

Wow, lesson four of 15 tick.

I'm ready for lesson five where we will be continuing our learning about decimals, and I think based on how hard you've been working in this lesson, you are ready as well.

If you have any other learning lined up for the day I hope you enjoy it, and I look forward to seeing you again soon for some more maths learning.

Bye.

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