Lesson video

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What do you think? Is this banana no longer yellow enough to eat? Has it become too spotty? Now when a banana is too green, I just leave it on the side to ripen.

But I wonder if I've left this one for too long.

Give me a thumbs up if you would still eat this banana.

Give me a thumbs down if it would be a no from you.

Oh I can't decide.

You know, I think I'm going to put it down.

Focus on the maths lesson, and see how hungry I am at the end.

If you're not yet in a quiet space, can you press pause, take yourself somewhere, where you're free of distraction, where you're able to focus on your learning with me for the next 20 minutes in this maths lesson.

Press pause now and come back when you're ready to start.

In this lesson, we will be multiplying and dividing by 100 with decimals.

Will starts off with an ordering decimals activity before we look at multiplying by 100 and then dividing by 100.

Looking at them separately, so that you're ready in your independent task to apply both of those skills.

The things that you'll need.

A pen or pencil, a rubber if you have one, a ruler, and a piece of paper or a book or pad.

Press pause, go and collect the items and come back when you're ready to start.

Right, an ordering decimals activity first.

Ordering on a number line.

Look at that number line.

Where does it start? Where does it end? Okay, that's what we know.

What we need to find out of course, is the position of those six decimals along that line.

Press pause, have a go of maybe drawing the number line, positioning the decimals and then come back when you're ready to check.

Should we take a look? Okay, so I know that I've got a space between zero and one that's worth one.

And I'm ordering decimals hundredths between it.

I'm not going to think about that space being divided into 100 equal parts, they would just be so small, and that would just be so many.

I'm going to think about that space, visualise it being divided into 10 equal parts.

Now that I visualised 10 equal parts.

I'm thinking right where would halfway be five tenths, 50 hundredths, they're equivalent.

That helps me to find 0.


It's six hundreds away from halfway from five tens from 50 hundreds.

And next.

This is between 0.

3 and 0.


It's smaller than halfway, it's closer to halfway than it is to 0 0.

11, just off the first 10th just off 10 hundredths 0.

14 I've positioned on the top of the number line, because it's fairly close to 0.


I didn't want the numbers to overlap.

Where would you put 0.

74 Show me on the number line just tap with your finger and see if that's where mine appears.

About there? Good it's almost three quarters so close to three quarters which is 75 hundredths.

So close to three quarters along that line.

Finally 0.

85, put your finger where that would be.

Around here good.

Hold up your number lines for me.

Looking good.

And you're comparing to mine which I have been able to.

To order along, because I've visualised a number line divided into 10 equal parts.

Did you visualise that? I wonder how you approached it.

And what you were thinking about.

That number line I mentioned, if I put it in now, we can see that where I've positioned my numbers may not be exactly right.

But it's a close estimate, based on that visualisation.

And I think visualising those 10 equal parts has really helped.


Multiply by 100.

Tell me what you can see.

One ten, four ones 14, we're going to multiply it by 100.

When we multiply by 100 each part of the number increases in size 100 times.

It gets 100 times bigger.

One ten, 100 times bigger is 1000.

And one one 100 times bigger is 100.

So, one ten and four ones, 14 one hundred times bigger becomes 1400.

Say the equation, One, two, three 14 multiplied by 100 is equal to 1400.

We've gone from 14 ones to 14 hundreds.

And we say those numbers as 14 and 1400.

Say what you can see 1.

4? Good.

Let's multiply it by 100.

Make one 100 times bigger, make four tenths, 100 times bigger.

How will this number change and what would it become? One hundred I didn't say 1000 100 and 40 each part 100 times bigger.

Okay, let's read the equation, one, two, three 1.

4 multiplied by 100 is equal to 140 Say what you can see.

Say it again.

Good 0.

14 multiplied by 100.

Make the one 10th 100 times bigger and make the four hundredths 100 times bigger.

What about those place value counters, not move to, but how will they change as the digits move.

Good one ten and four ones, 14.

Can we whisper the equation one, two, three 0.

14 multiplied by 100 is equal to 14.

I think you're ready for a practise of multiplying by 100.

Pick any of these numbers represent it with a drawing of place value counters and a place value chart.

Multiply it by 100 and write the equation.

Use more drawings to.

Again have place value counters to show how the number has changed.

Press pause go and have a go at practising this skill and come back when you're ready.

How did you get on? Can you hold up anything that you've been drawing any pieces of paper with your work on let me see.

So I'm looking out for place value grids.

I can see one there.

See another one there, good.

I'm looking for place value counters.

Good now I'm looking of those counters representing the numbers you had to choose from.

And there were eight.

And I'm looking for place value counters to represent numbers that are not on this screen, but are the result of multiplying by 100.

So for example, can I see anywhere place value counters representing 7300? Yes I can.

Because you multiplied 73 by 100.

Okay, who has got a drawing of 340? Which number did you multiply by 100? 3.



And last one who has a drawing of 56? 5 times six ones, you do, good.

Because you multiplied which number by 100 0.

56 really good work.

Let's now think about dividing by 100.

Again, say what you can see.

Three thousands, one hundreds, that's the number 3100 good.

Let's divide by 100.

When we divide by 100, each part of the number becomes 100 times smaller.

One ten is 100 times smaller than 1000.

So three thousands 100 times smaller, will be 3 tens and 100 times smaller, will be one 31.

Read the equation to me, please.

One, two, three Good, say what you can see.

310 Good.

Let's divide by 100 make each part 100 times smaller.

Instead of three hundreds.

We will only have three ones, and the one ten has become one 10th, 3.


Let's whisper the equation together.

Three hundred ten and divided by 100 is equal to 3.



Okey last one, say what you can see three tens, one ones, 31? Let's divide by 10.

No, let's divide by 100.

Thank you.

Divide by 100 make each part 100 times smaller three tens will become, and one one will become, let's say, Good 0.


Let's say the equation.

I'll read the first part, you read the second part.

Carry on when I stop 31 divided by one Hundred.


Let's compare division and multiplication.

Can you read the division equation to me? Good.

My turn 31 multiplied by 100 is equal to 3100.

My turn.

310 divided by 100 is equal to 3.


Your turn Good, your turn.

My turn, 0.

31 multiplied by 100 is equal to 31.

Look at the patterns, look down the division and down the multiplication.

And look across the division and the multiplication.

Look at the numbers becoming 100 times smaller when we divide and becoming 100 times bigger when we multiply by 100.

And when we divide by 100.

Lots of connections, patterns, to spot.

Almost time for your independent task.

You're going to have some function machines.

These are function machines.

Look at the first one, 0.

5 inside the arrow it says multiply by 10.

Okay, so do that, perform that action 0.

5 multiplied by 10 is equal to 0.



You've completed that part of the function machine.

Look at the bottom.


5 add 0.

1 is something divided by 10 is something.

We've got two actions now.

So 0.

5 add 0.

1 is.


Then 0.

6 divided by 10, 0.


You've completed two machines.

By filling in the parts, that are the result of an action.

Press pause, go and complete your activity where you've got even more function machines to complete.

Come back when you're ready to check.

Should we look? This was your first part.

So what did you get? 28, 37 and 40.


Hold on let me see how you've got on so far.

Good work.

The next two.

It's a bit like working backwards.


82, not divided by 100 but Multiplied by 100 will give us that first number.

What did you get for that? 82.

82 divided by 100 is 0.

82 0.

82 multiplied by 100 is 82.

How about the last one? Good 0.

05 multiplied by 10 is 0.

5 0.

5 divided by 10 is 0.


We can work forwards and backwards, changing our operation to help us find the missing numbers.

How did you get on this side? Shall we look? Good.

Add 0.

1 divided by 10.

Next, multiply by 100, and then subtract 20.

Good, subtract 0.


subtract two hundreds will have seven hundreds, then multiply by by 100 We'll have seven Oh, the last two.

we've ever got missing actions or missing numbers 0.

02 something is 0.

2 The number has increased in size by 10 10 times bigger multiplied by 10.

Now is increased, we had two tenths, we've now got six tenths, it's increased by four tenths, we've added four tenths Let's work backwards for this last one.


2 divide.

Multiplied by 10 is 72.

Add subtract 46 is 26 26 add 46 is 72 72 divided by 10 is 7.


Really good work everyone.

I hope you enjoyed this function machines working forwards, working backwards, multiplying, dividing, adding, subtracting, I hope you had a lot of fun with them.

Final task before we end the session, what could the functions be? How many different solutions can you find? 0.

3, something something something.

Wow, finishing with 0.


Press pause, go and have a go with this problem and see how you get on.

Come back when you're ready for a solution.

How did do? Challenging? Did it make you think? Is your brain hurting a little bit now? Then good, good.

I wanted to it shows that you're making lots of connections.

It shows that you're trying to retrieve things that you already know, and maybe connect them to the new skills of multiplying and dividing by 100.

Okay, hold up your paper if you managed to get the solution that you think worked.


And if you didn't manage, would you like to know a solution? Yes.

Okay, here we go.

So multiply by 10 is equal to three, add two is equal to five divide by 100 is equal to 0.


So we've worked there we work to there with some multiplying by 10 and dividing by 100.

That's a solution that worked for me.

Did you have a different solution? Could that be another solution? If you'd like to investigate whether there's another way of solving this, take a picture maybe of the screen right now or pause it and play around with the numbers and the functions I've chosen, make some changes.

See if you can make it work still, but with different numbers and functions.

If not we are finished.

If you'd like to share any of your work with Oak National, please ask your parents or carer to share your work on Twitter tagging @OakNational and #LearnwithOak.

Wow, wow.

Wow, what a fantastic lesson.

Thank you so much for joining me, for engaging, calling out, saying numbers saying sentences, holding your work up at the camera.

Thank you for taking part.

Do you know that was lesson 15 of 15 in this unit, I have enjoyed every single lesson.

Every opportunity to teach you more about decimals.

Whether you have joined for one lesson, for two lessons, or 15.

A huge thank you for me for joining.

There's only one last question.

Is Mr. Whitehead going to eat this not quite yellow, slightly too spotty banana.

Well, my brain has been working overdrive in this lesson and I have certainly worked up an appetite.

An appetite big enough to tackle this not quite yellow banana.

So it's a yes from me.

Thank you again for joining, See you again soon.