# Lesson video

In progress...

Hi everyone.

Ms. Hill here.

Today we are doing a lesson using bar models to solve word problems. It's going to be a really fun lesson today, so make sure you've got those mathematical hats on, so put on your hats, tighten your ties, and tell the computer "Now I'm a mathematician".

Let's get started.

Here is our lesson agenda for today.

First off we're going to our star words.

We're then going to be looking at a big picture, before having a think and doing some exploring, before moving on to independent task and the quiz.

Before we get started, please make sure you have a pencil, a piece of paper, and a ruler with you.

If you need to pause this video, then please do and get all the bits that you need.

Let's have a look at our star words.

Well done.

So we have our strategy, total, pounds, pence, part, whole, bar model.

Can you show me pounds? Can you show me pence? Can you show your bar model? Great job everyone.

So here we have our big picture.

This is a river in Cambridge, and as you can see there are some students on the punts, and they're pushing people around the canals.

At every university, there is a student union.

And in the student union you can buy some items. So we have rulers which are 42 pence.

We have 27p pencils, rubbers, which are 40 pence, pens are 35 pence, and paperclips that are 8 pence.

This student is from King's College.

He bought a rubber and a ruler.

But how much did he spend? This is an opportunity for us to use our bar models in order to find the total amount of money spent.

Here we have our two parts and we need to add them together to create our whole.

And I'm going to use some of our number knowledge.

If I know that four add four is equal to eight, then I know that 40 add 40 will be equal to 80.

And then we have two ones.

80 add two is equal to 82.

But remember to use your units of measurement, which in this case is pence.

So our student spent 82 pence.

So it's your turn to go shopping now.

Here we have the same items that he might have bought.

The ruler, the pencil, the rubber, the pen, and the paperclip.

And what you need to do is you're going to do some shopping.

Let me show you what I would do.

So I've got my pen and I've got a whiteboard instead of a piece of paper.

I'm going to pick the rubber at 40 p.

I'm also going to pick, hmm what do I need? I need a pencil, which is 27 p.

So here you can see I have got one part, which is 40 pence, and I have a second part, which is 27 pence, and I need to work out the total.

So I'm going to add 40 pence and 27 pence.

And I'm going to use my number knowledge.

If I know that 4 add 2 is equal to 6, then I know that 40 add 20 is equal to 60.

And 60 add 7 pence is equal to 67 pence.

So I spent 67 pence in the shop.

How much are you going to spend? Pause this video before you do some shopping.

Great job.

Let's have a look at some word problems together.

On a trip to Cambridge, Andrew had a 20 pound note to spend in the gift shop.

He bought a T-shirt for seven pounds and a map for eight pounds.

But how much change did he get? So what we need to do is to follow our steps to success.

Step two, identify key information.

Well, my key information is that he has 20 pounds to spend, he's bought a T-shirt worth seven pounds, and a map worth eight pounds.

So I know that the equation I need to do is seven pounds plus eight pounds.

And I've even drawn my bar model.

So we have seven pounds plus eight pounds.

There's a much nicer one there.

And when you add the two together, you get the total of 15 pounds.

However, I haven't finished, because he spent 15 pounds, and I need to work out the change.

So 20 take away 15, we need to find the difference.

The difference is five pounds.

You have three questions.

So first you need to read the question carefully, identify and underline the key information, write the equation and create your bar model, and then you're going to answer it.

Remember to pause this video while completing the task.

Great job everybody.

Let's have a look at these questions together.

Question number one.

He bought a T-shirt for seven pounds, and a key ring for four pounds.

How much change did he get? Well we know our two parts in seven and four, and I know that seven add four is 11 pounds.

But we're not finished there.

I need to remember to work out the change.

20 take away 11 pounds is equal to nine pounds.

Question number two.

She bought a mug for five pounds, a bookmark for three pounds, and a key ring for four pounds.

How much change did she get? So I know I need to add three parts together.

Five add four is equal to nine, add three is equal to 12.

But have I finished there? No I haven't, have I? I still need to work out the change.

And I can use a number bond here.

Because if I know that two add eight is equal to 20, Ooh! No it's not.

Two add eight is equal to ten, then I know 12 add eight is equal to 20.

So 20 take away eight is equal to 12.

After she bought her two items she had three pound change.

One item she bought was a model punt for 11 pounds.

How much did the other item cost? Now this is an interesting one because its worded a bit differently.

So we know she had 20 pounds to spend.

And we know she got three pounds change.

So in total, she spent.

Well 20 take away three is equal to 17.

One item she bought was 11 pounds.

How much did the other item cost? So if the total was 17, and one of the parts was 11, then the other part must be six.

And we can check it, 20 take away 17 is equal to three.