Lesson video

Hi, everyone.

It's Ms. Mitchell here.

It's great to see you all.

I hope you're all ready for a maths lesson today.

Today, we're going to be representing two-step word problems using bar models.

In today's lesson, we'll be representing two-step word problems using bar models.

We will then be drawing bar models, then I'd like you to complete the worksheet and then the quiz.

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

Pause this video now to get this, if you have not got it already.

Here's a word problem.

There were 50 children in the school hall, 20 more children arrive in the hall, then 40 children leave the hall.

How many children are in the school hall now? How can I represent the maths in this word problem using the bar model? For this word problem, there are two steps.

So I'm going to draw two separate bar models to help me solve this.

I can see that I start with 50 children, and that's why I need to add 20 more.

When I am adding more, the number will get bigger.

50 is one of my parts, and 20 is another part.

The whole is the unknown.

So I'm going to draw my bar for 50 and label it.

Then I'm going to draw my second part of 20 and label it.

And the whole is the unknown.

I now need to write my equation.

50 plus 20 is equal to the unknown.

Now, I can solve my equation.

50 plus 20 is equal to 70.

I now need to answer the second step of my word problem.

Then 40 children leave the hall.

How many are there now? People are leaving, so the number will be getting smaller.

So we are subtracting.

70 is my whole.

And 40 of the 70 leave.

So 40 is one part.

The other part is what is unknown and what we need to solve as this is how many are in the hall now.

To find out the unknown part, my equation will be 70 subtract 40 is equal to the unknown.

I can now solve this.

70 take away 40 is equal to 30.

Let's try another one together.

So have your pencil, ruler, and paper ready.

There were 26 people on the top deck of the bus.

There were 32 people on the bottom deck of the bus.

Then 24 people left the bus.

How many people were left on the bus? We're going to start with the first step.

I can see that my first part is 26, as there were 26 people on the top deck.

And my other part is 32 because there are 32 people on the bottom deck.

To move on to the next step of the question, I need to work out how many people are on the bus altogether now.

So I'm going to draw my bar for 26 and label it.

I draw my part for 32 and label it.

And the whole is the unknown value.

I now need to write this equation.

26 plus 32 is equal to the unknown.

Now, I can solve my equation.

26 plus 32 is equal to 58.

Pause the video here, if you need to finish your bar model for the first step of the word problem.

I now need to answer the second step of my work problem.

24 people left the bus.

How many people were left on the bus? People are leaving.

So again, the number will be getting smaller, so we are subtracting.

58 is my whole, and 24 is one part.

The other part is what is unknown and what we need to solve.

To find out the unknown part, my equation will be 58 take away 24, which is equal to the unknown.

I can now solve this.

58 take away 24 is equal to 34.

Pause the video here, if you need to finish your bar model for the first step of the question.

Have a go at solving this two-step word problem by yourself.

40 children are already in the school hall.

30 more children arrive.

Then 50 children leave.

How many children are in the hall now? Pause the video to draw your two bar models to help you solve this equation.

Let's start with the first step.

I can see that my first part is 40, as there were 40 children in the school hall.

And then 30 more arrive.

The word more shows us that my number will be getting bigger.

These are my two parts because I need to find out how many children are in the school hall.

So I'm going to draw my bar for 40 and label it.

I then draw my part for 30 and label that.

And the whole is the unknown value and what I need to solve.

I now need to write this equation.

40 plus 30 is equal to the unknown.

And I know that 40 plus 30 is equal to 70.

Great.

I hope you're with me so far.

If not, why not re-watch that part again? We are now moving on to the second part of the question.

50 children leave.

How many children are in the hall now? Children are leaving, so that gives me a clue that we are subtracting.

70 is my whole.

And 50 of these 70 leave, so 50 is a part.

The other part is what is unknown and what we need to solve.

To find out the unknown part, my equation will be 70 take away 50 is equal to the unknown.

I can now solve this.

70 take away 50 is equal to 20.

There are 20 children in the hall now.

Pause the video here if you need to finish your bar model.

Well done.

Why don't we do just one more before your independent worksheet? There were 54 children in the playground.

42 more children arrive.

Then 31 children leave.

How many children are there now? Pause the video here to draw your two bar models to help you solve this equation.

Let's start with the first step.

I can see that my first part is 54, as there were 54 children in the playground.

And then 42 more arrive.

The word more shows us that my number will be getting bigger.

These are my two parts because I need to find out how many children are in the playground.

So I'm going to draw my bar.

And my first part is 54, so I'll label it.

Then I'll draw my part, which is 42, and label that.

And the whole is the unknown value.

I now need to write this equation.

54 plus 42 is equal to the unknown.

And I know that 54 plus 42 is equal to 96.

I now need to answer the second step of my word problem.

31 children leave.

How many children are there now? 96 is my whole, as there are 96 children at the moment in the playground.

And 31 of these 96 leave.

So 31 is part of the whole.

The other part is what is unknown and what we need to solve.

To find out the unknown part, my equation will be 96 take away 31 is equal to the unknown.

I can now solve this.

96 take away 31 is equal to 65.

There are 65 children now in the playground.

You've done really well.

Have a go at answering these word problems. Draw the bar models and label them.

Then work out the equation and solve it.

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

And here are the answers to your word problems. If you'd like to share your work with Oak National, then please ask a parent or carer to share your work on Twitter, tagging @OakNational and #LearnwithOak.

You've worked really hard and done so much learning.

Now, let's see what you can remember.

Go and complete the quiz right now.

See you later.