# Lesson video

In progress...

Hello and welcome to today's maths lesson on multiplication and division.

My name's Ms Thomas and I'll be going through the lesson with you today, I'm really looking forward to it, so let's not waste any more time and let's get started.

In today's lesson agenda, first we'll be exploring how to represent two-step word problems using bar models, then we'll move onto our Talk Task where you can have a practise.

After than we'll learn how to represent and solve division word problems, finally we'll finish off with a quiz where you can test yourself on your memory.

For today's lesson you're going to need a pencil, paper, and a ruler.

Pause the video now if you need to get your equipment.

We have two star words, the first is part.

Part means one amount that makes up a whole.

The second word is whole.

Whole means complete, including all of the parts.

Let's lock those in our minds because they will be important in our learning.

Here we have a word problem.

Read the problem out loud and decide what is the maths that needs to be done to solve the problem.

Pause the video now and answer the question.

Great job.

You might have notices that Mr Slade treats his children and their friends to a burger each for £3.

We need to underline that information because it's key for the maths that I need.

And he buys large fizzy drink for £2.

I'll also underline that key information too.

These are the parts, £3 and £2.

How much does each meal cost? That's the whole, that's what we want to find out.

However, you might have also spotted there are two steps to this word problem.

As it says if there are eight people eating, how much does the meal cost altogether? We're going to represent our word problem using a bar model to help us understand how to solve it.

So let's explore the first part of the problem.

In the first part of the problems it says that Mr Slade treats his children and their friends to a burger each for £3 and large fizzy drink for £2.

How much does each meal cost? We're going to answer the question below.

Well, in the first step you start with the parts, because we don't know what the total cost is yet which is our whole.

Next, it says is there more than one part? Well yes, there are two parts, £3 and £2.

Finally, are all the parts of equal value? No, because 3 and 4-- 3 and 2, are not equal.

When I draw my bar model I'm going to draw two bars and they are not equal because 3 is greater than 2.

That's my bar for the £3 and there's my bar for my £2.

I need to find the whole to find out how much each meal costs for one person.

So how do I find the whole? Pause the video now and decide how to find the whole for step one.

Great job, I can see unequal parts.

This tells I need to add because equal parts tell me I need to multiply.

Unequal parts shows me I need to add.

A good bar model should help you spot the operation you need.

I know I now need to add £2 and £3 which is equal to £5, to solve the first step for my problem.

This tells me that Mr Slade spent £5 on each child.

Next, let's explore the second part of the problem.

I'm going to call out the questions and you need to call out the answers So, first question, do you start with the whole or with the parts? Great job, we don't know the whole yet so we start with the parts, which we actually--and you might have spotted this too, we actually already worked that out in the first step.

It's £5 because that's how much he spent on each child.

Okay the first part of the problem is there.

Now the next question, are you ready? Is there more than one part? Pause the video and call out your answer.

Yes! You may have found that there are in fact eight parts because eight people are eating.

Last question, don't forget to pause the video and call out your answer.

Are all the parts of equal value? Yes, the parts are equal, the value of the parts is £5 and we need eight parts.

Add my eight parts onto my bar model.

So let's recap now.

I know that unequal parts in the bar model means I must add or subtract, and equal parts tell me to multiply.

Pause the video now and decide what calculation do you need to do to find the whole of this bar model.

Fantastic work, you should have said that I know I need to multiply five by eight, because I want to find out how much the meal cost altogether, and there are eight equal parts with a value of five.

This will tell me the whole.

Five times eight is equal to, you've got it, forty.

Great job, well done.

Read the word problem and find the key information, then match each step of the word problem to the bar model that represents it.

Then we're looking at two step word problems to find each step that matches the bar below.

Pause the video now and have a go at matching.

Fantastic matching work.

Let's take a look at the answers.

I'm going to read the problem, so read along with me, off we go.

Ali is putting up the wallpaper in some new houses before their owners move in.

The upstairs of one house needs 6 metres of paper and the downstairs needs 3 metres of paper.

How much paper is needed for one house? If there eight houses, how much paper will he need altogether.

Well, before we can find out how much paper he needs altogether for eight houses, we need to find out how much he needs in one of those houses.

And then we can splice that answer by eight.

I've underlined the first part of the two step word problem.

This will tell me how much paper he needs for one house.

And we need to do 3 metres plus 4 metres, which is equal Y metres.

The parts are not equal so I must add them.

This is the correct bar model.

Here is the second step, this tells me how I need eight equal groups of nine metres.

Here is my bar model.

The parts are equal so I must times them.

Give yourselves thumbs up for the talk task, and don't forget to pause the video and correct any work that you made a mistake.

Don't worry, we love mistakes, that's how we learn best.

Let's recap again.

So we've got Abdinafi and Efrain here, and I've got some questions I would you and them to have a think about.

You might want to pause the video and have a think if you need the time.

First question, what do we know about the value of the parts in a multiplication bar model? Great work, you might have agreed with Efrain and said that the parts should be equal in a multiplication equation bar model.

Well done if you agree.

Let's look at the next and final question.

How does this-- how do these equal parts in a bar model help us to solve division calculations? Pause the video and think.

Abdinafi correctly answered, division and multiplication are the inverse operations.

The parts of division calculations are also equal.

So we now know that the parts of multiplication bar models are equal and the parts in division equations of the bar model are equal because they are the inverse operation, they are opposite.

Let's keep that locked in our mind because that's important for the next part of the lesson.

Now we're going to represent and solve multi-step word problems including division.

Let's read the word problem together.

After winning 33 marbles on Monday, and another 31 marbles on Tuesday, she shares them fairly between India, Erin, Deepak, Polly, Arun, Tegan, Christie and Yenn.

How many marbles will each of her friends get? Pause the video now and have a think and find the first part of the problem.

Remember there are two steps to this problem, find the first step, and then create your bar model to represent it.

Off you go, pause the video now.

Great job, you should have found that this is the first step of the problem.

You need to add the unequal parts 33 and 31 to find the whole, which is 64.

Next, pause the video and find the second step in the problem and draw your bar to represent it.

Pause the video now.

Great job, you should have found that this is the second part of the word--the second step, sorry, of the word problem.

The whole is the answer from step one, and now we are sharing marbles equally by eight.

Because there are eight people.

Do you need any calculation--do you know, sorry, any calculations that have a whole of 64 and equal parts with a value of 8? So, do we know of any calculations that have a whole of 64 and equal parts with a value of 8? Pause the video now and have a think.

Fantastic, yes you may have realised that we know that 8 times 8 is equal to 64.

It's super important to use our multiplication facts.

We knew we would use multiplication because the parts were equal.

Fantastic work so far.

We're now ready for independent task, where you will be representing two step word problems using bar models.

Remember two step word problems will mean two bar models.

Pause the video now and show off your fantastic bar model representations.

Excellent job, lets go through the answers together.

Now is your chance to tick them of as we answer them, and correct any representations that you got wrong.

Compare your bar models to mine as we go through.

So for the first word problem, these are two bar models you should have drawn, and your answer 7 packs.

The second here are my two bar model representations and the answer 32 minutes.

The third one, here are my two bar models and my answer £24.

And finally, my two bar models to represent my word problem and the answer 10 litres.

Pause the video and now and give yourself time to just go through and check that your bar models are the same as mine.

And you've got some time to pause and correct any mistakes.

Don't worry though we love mistakes that's how we learn best.

Excellent learning today.

If you'd like to, please ask your parent or carer to share your work on twitter, tagging @OakNational and #LearnwithOak Excellent job, the time's now come to complete your quiz to see just how much you've remembered from the lesson today.

I'm sure it's going to be loads.

Good luck, and see you next time.