Lesson video

In progress...

Hi everyone, it's Miss Mitchell here.

Today in math we're going to be applying up knowledge of bar models to a range of word problems. In today's lesson we'll be applying knowledge of bar models to answer word problems. We'll be looking at a range of word problems, we'll be completing some challenges, and then I'd like you to try a quiz.

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

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

Here is a word problem.

There are 51 apples and 25 oranges.

How many pieces of fruit are there altogether? Pause the video now to draw a bar model to represent this problem.

In this question I can see that one part is 51 apples.

I can see my other part is 21 oranges.

The whole is unknown because it's asking me how many there are altogether.

What will my equation be? 51 plus 25 is equal to the unknown.

We can now answer this equation.

51 plus 25 is equal to 76.

Let's try a different question.

There were 19 bananas at the fruit stall.

Eight of them were green.

How many were yellow? Pause the video now to draw a bar model to represent this problem, and then answer the question.

From this question, I can see that there are 19 bananas.

Eight of these 19 were green.

Therefore, 19 is my whole and eight is a part.

This part here is the unknown.

By looking at this bar model, what will my equation be to solve this problem? That's right.

19 take away eight is equal to 11.

Well done.

Here is a new problem.

There was 60 children in the school hall.

20 more children arrive in the hall.

Then, 70 children leave the hall.

How many children are in the school hall now? Pause the video now to draw a bar model, to represent this problem, and then answer the question.

This is a two step problem.

So I would draw two bar models, one for each step.

There were 60 children in the school hall.

20 more children arrive in the hall.

What is known? We know that there are 60 children and 20 more arrive.

We need to know how many children there are in the hall.

Therefore, 60 is my first part, and 20 is my second part.

We need to work out the whole, and the whole is unknown.

How do we work out the whole? What will my equation be? 60 plus 20 is equal to the unknown.

We can now answer the equation.

60 plus 20 is equal to 80.

Now we've answered the first part.

We can answer the second part of the question.

Then, 70 children leave the hall.

How many children are in the school hall now? Our whole is 80 and then 70 of those 80 leave.

So 80 is my whole and 70 is a part.

This part here is the unknown.

Now I've drawn my bar model.

I can work out what my equation is.

What will my equation be? 80 takeaway 70 is equal to the unknown.

Now we can solve this.

80 takeaway 70 is equal to 10.

Here is a different question.

James has six pens.

Sheri has three more.

How many pens does Sheri have? Pause the video now to draw this as a bar model, then answer the question.

In this question, I am comparing James and Sheri.

So this will be a comparative bar model.

What information do I know? I know James has six pens.

I know that Sheri has three more.

So Sheri has six pens, plus the three more.

Now I can see how many pens Sheri has.

I know that James has six pens.

I can now see from my bar model that Sheri has nine pens.

Here, is the same amount of pens they have.

And then Sheri has the three more.

How many more pens does Sheri have? Three more than James.

So that means that James has three fewer pens than Sheri.

Can you work out the difference? I know the difference is three, because nine takeaway six is equal to three.

Here is a word problem.

Anne picked 19 apples and ate seven of them.

How many apples were left? Here is a bar model to represent the math, but I've accidentally made a mistake.

Can you help me find it and tell me why? Pause the video now.

The mistake is here.

19 should be the whole.

And seven is a part.

And this part here is the unknown, or should be the unknown.

Well done for spotting it.

Here I've created a bar model.

But can you create a question for the bar model? Here is my example.

I know that the whole is 18, and one part is 15.

The unknown is the other part.

So I know I can't create an altogether question because that's when I don't know the whole.

This means it could be a, how many are left question? For example, there are 18 pieces of chocolate.

Miss Mitchell ate 15 pieces.

How many are left? Can you pause the video to create your own question for this bar model? Here's a different bar model.

Can you create a different word problem to match this problem? Here's my example.

How many more stickers did Billy have? And then the answer could be, 20 more will be 24.

Pause the video now so you can have a go.

Here are three word problems. Can you match them to the correct bar model? Pause the video to read the questions and then match them to the bar model.

I know this first question matches to this bar model here, because it is unknown how many more books that Megan has.

But the second question, it matches to this bar model over here, because the unknown is how many there are altogether.

And altogether means my whole.

And this third one here matches to this word problem, because it is unknown how many books Sally has.

That was the last lesson of the unit.

It showed all the different types of questions on bar models in this unit.

Well done for completing the lesson.