Lesson video

Hi, everyone.

I'm Miss Mitchell.

Today we're going to be representing information as a bar model.

In today's lesson, we will be solving addition word problems, solving subtraction word problems, then I'd like to have a go at the worksheet and then a quiz.

For today's lesson you will need a pencil and some paper.

Pause this video now to get this if you've not got it already.

Here is a word problem.

Four people were on the bus, then two more people got on the bus.

How many people are on the bus now? How can I represent this word problem in a part whole model? What are the values of my parts? The value of one part is four cause four people were on the bus.

And the other part is two, because two more people got on.

The whole is the unknown value.

This means we don't know what the whole is, and that is what we need to find out.

I can write this as an equation.

The equation is four plus two is equal to the unknown.

We can represent the maths in the word problem, using another representation, A bar model.

Just like in the part whole model, the value of one part is four, and the other part is two.

I know by looking at this bar model, that four plus two is equal to six.

So the answer is six.

And if you count, you can see six cubes in the bar model.

one, two, three, four, five, six.

Let us try one together.

There are two people on the bus.

Six more people get on the bus.

How many people are on the bus now? What is known and what is the unknown value? Can you draw a bar model to represent this math problem? Pause the video and have a go.

I know that one part is two.

And I know the other part is six.

The whole is the unknown value.

So my equation will be two plus six is equal to the unknown.

And here is the answer.

Did your bar model look similar to this? There are 14 people on the bus.

Then five people get on the bus.

How many people are on the bus now? Can you have a go at this one by yourself? Represent the word problem as a bar model.

Don't forget to write your equation.

Pause the video and have a go.

And here is the answer.

Your bar model should look like this.

We know one part is 14 and the other part is five.

The whole is the unknown value.

Because I know my parts and the whole is the unknown, I know I will be adding.

Always remember to write your equation.

By looking at this bar model, we can then solve our equation.

I know that 14 plus five is equal to 19.

Let's try a different problem.

Can you work out why this question is different to the previous questions? The ones before? It's different because we will be using subtraction.

We know that the whole is six because six people are on the bus.

We know that one part is four because four people get off the bus.

The other part is the unknown value because we don't know how many are on the bus now.

People are getting off the bus.

That shows us that the answer will be getting smaller.

My equation will be, six subtract four is equal to the unknown.

We can represent the maths in the subtraction word problem by using a bar model.

Just like in the part whole model, the value of the whole is six and one part is four.

The other part is the unknown and what's we are trying to work out.

I know by looking at this bar model, that six take away four is equal to two.

So the answer is two.

Let's try one together.

There are eight people on the bus.

Then two people get off the bus.

How many people are on the bus now? What do we know and what is the unknown value? Can you draw a bar model to represent this maths problem? Remember to write your equation.

Pause the video to have a go.

I know that the whole is eight because I start with eight.

And then one part is two, because two people get off the bus.

The other part is the unknown, which is what we're going to solve.

Did you remember to write your equation? My equation would be eight take away two is equal to the unknown.

And then by looking at this bar model and equation, I know that eight take away two is equal to six.

Let's try one final question.

There are 19 people on the bus.

Then five people get off the bus.

How many people are on the bus now? Have a go at this one by yourself.

Right, present the word problem as a bar model and write the equation.

Pause the video to have a go.

Does your bar model look like this? We know that the whole is 19.

Because there were 19 people on the bus.

One part is five because five people got off the bus, but the other part is unknown.

My bar model, has helped me understand the question and helped me write the equation.

So now I can solve it.

19 take away five is equal to 14.

Have a go at answering these word problems. First, you need to read the question and work out what operation to use, whether it's addition or subtraction.

I like to underline any key words or numbers in the question too.

Then draw your bar models and work out the answer.

Pause the video now, and then press play when you're ready for the answers.

And here are your answers.

Well done for giving it a go.

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

That's the end of learning today.

You've done a great job and I hope you're proud of yourself.

I want to see what you have learned.

So please make sure when the video has finished, you go onto the next slide and you complete the quiz.

Well done.