Lesson video

Hello everyone, I'm Mrs Crane and welcome to today's lesson.

In today's lesson, we're going to be looking at how we can represent a one-step word problem.

In a moment, I'll go through all of the equipment we need so don't worry about getting that just yet.

If you can please turn off any notifications that you have on either your phone, tablet or whatever device that you're using to access today's lesson on.

And then you can try and find somewhere nice and quiet in your home where you're not going to be disturbed.

When you're ready, let's begin.

Okay, then let's run through today's lesson agenda.

First, we're going to start off by looking at what is known and what is unknown.

Then we're going to look at today's let's explore which we'll be looking at bar models and word problems. Then we're going to let more in depth at word problems themselves.

And then we're going to look at how we can represent a problem in your independent task.

And we'll go through the answers together at the end.

So before we get started, can you please make sure that you've got yourself a pencil and some paper.

Please pause the video and ask or get those things, if you haven't got them already.

Okay, welcome back.

Let's get started then.

What is known and what is unknown? I'm having a look at this bar model here.

You can see it on the screen.

What information do we know from this bar model? Will need you to have a little think, what do we know from this bar model? Well, I know there are two parts and I know that the first part here is worth 1,347.

And then my second part here is worth 1,412.

Do I know what my whole is at the moment? By technique I do.

So my first question was, do I know the whole? Do I know the whole? What do you think? I don't think I know the whole right now.

My second question is, what equations would this represent? Can you think of any equations that it would represent? Well, let's have a look.

So I could say, that 1,347, so our first part here, plus 1,412 is equal to my question mark, because I know that they equal up because my bar model shows me that they do.

But I just don't know what my question mark represents.

Or I could say question mark take away 1,347.

It's going to leave me with 1,412, or I could say question mark, take away 1,412, is going to leave me with 1,347.

The thing that I don't know at the moment is what that question mark presents.

So, how could I represent this in a word problem? Before we solve that, I want us to think about how we could represent this as a word problem that this bar model is showing.

A real life problem that might need solving.

So I've come up with the problem.

You might have a different problem.

Mrs Crane baked 1,347 chocolate cupcakes, my favourite.

And 1,412 lemon drizzle cupcakes.

A good second best.

I mean, I didn't bake as many of them, but they aren't my actual favourite.

How many cupcakes did she bake altogether? Well, I know she baked a lot of cupcakes, but I don't know how many she made altogether.

That question mark here.

I do know these two values.

My two parts though.

So using those equations that we looked at before and using this word problem to give my bar model a real meaning, we're going to have a look at how we solve that.

So as I say, we're solving our problem.

I know I need to add them together to give me my question mark.

So when I'm going to add them together, I'm going to use the column method, it's going to be the quickest, most efficient way of adding here.

So I'm going to do seven add two, it's going to give me nine.

Four add one, gives me five.

Three add four, gives me seven.

Of course, I know that it's not really three or four.

Those are in the hundreds column.

So those digits represent hundreds.

But for the sake of us going through it, we're not going to say those each time.

One, add one is equal to two.

So my answer, how many cupcakes did I bake altogether? Well, I made 2,759 cupcakes altogether.

How could we check our answer? Could we do something to check that I've answered that correctly? Absolutely, we could use the inverse.

Now we're going to use the inverse to take our whole and subtract one of the parts away from it to see if it equals our other part.

One of those calculations that we looked at in our previous slide.

So let's take our whole and this time I'm going to take away 1,412 from my whole.

So which column do I start on when I'm doing column subtraction.

Absolutely, I have to start with my ones column.

So nine take away two is equal to seven.

Five take away one is equal to four.

Seven take away four is equal to three, two take away one is equal to one.

So my answer, 1,347.

Have I got it correct? Is it the same as the other part? Absolutely, I have.

So well done Mrs Crane.

Now, if you're feeling really confident, I want you to have a think about what you know, what is known, sorry, and what is unknown about this bar model here and have a guy, if you can at writing your own word problem to represent it.

Pause the screen now if you really want to have it go at this.

You don't end up getting so confident, it's okay, because we're going to go through this together now.

So I notice this time, is that I can see the big bridge, I guess you could call it.

The jump across the whole of my bar model is known which tells me, that this time, I do know the whole.

I know the whole and the whole is 4,895.

This time, I don't know this part here.

My question mark here.

So I don't know one of the parts, but I do know the other part.

So what equations could this represent or would this represent? Have a subtle think? What's the equation, would this represent? What if I wanted to find out my question mark, I need to do either, for 3,253 plus something.

That question mark.

I know it's going to give me 4,895, or I can do 4,895 subtract something and it's going to give me 3,253.

Can I do either of those equations at the moment? I can, there's going to be another equation I'm going to have to do before I can solve this equation.

Well, in order to solve this equation.

Not before I can solve it.

So before we look at that and how exactly I need to write it, think.

What word problem could we come up with this time? Can you think of a word problem? Well, here's mine.

Mrs Crane took 4,895 orders for donuts during one week in August.

My donuts are very popular.

I can't actually make donuts.

You probably wouldn't want to taste them, if I could.

She received 3,253 of the orders at the weekend.

Ooh, quite a lot of orders that when we can, you can see here.

Lots of people are ordering their donuts for the weekend.

How many did she receive during the week? What I know it's not going to be as many because I can see that my bar model represents a smaller amount, but I need to work out how many.

So can you see this question? This bar model here.

So I've written this question based on this bar model.

Now, as I said before, we couldn't do those two equations because the equations had the question mark within them, but the equation that we can do to work out the question mark is 4,895 subtract one of our parts.

The part that we know, 3,253.

So you can see here.

I can put that down here.

So five oh, which column do we start at? Absolutely, I was ready to go already, start with our one's column.

Five subtract three is equal to two.

Nine, subtract five is equal to four.

Eight subtract two is equal to six and four subtract three is equal to one.

I completely finished or could I do something? Could I check my answer using the inverse? So this time I'm going to take both of my parts because I've given my answers to other parts of my bar model.

And I'm going to see if it gives me my whole, the number 4,895.

So two add three is five.

Four add five is nine.

Six add two is eight.

One add three is four.

Absolutely does give me my whole again here.

So I know I haven't gone terribly wrong in my subtracting and I've got the correct answer.

Okay then, it's now time for today's let's explore.

We're going to be looking at bar models and word problems, just like we've been looking out.

So I'm just going to hide myself for a moment, so you can see all of the bar models.

So you have got four bar models here.

You can choose which one you would like to use.

If you want to, you can challenge yourself and use more than one.

I'd like you to think, what is your word problem going to be? So that you can use the words, my word problem is.

What would your calculation be? So the calculation would be, I know the, and the, I don't know the, so do you know the whole and one part? Do you know both parts, but not the whole? Have a look really closely at the bar model you're choosing to use before you can answer that final question.

Please pause the video now, to have a go at today's, let's explore.

Okay, welcome back.

Right then, what's known and what is unknown? So we're going to think about what the bar model will look like, that is for this word problem.

So previously we've been looking at the bar model first and then coming up with a word problem.

This time we're going to do it the other way round.

So Mrs Crane employs 1,368 people at her bakery shops and 2,461 in the bakery factory, baking factory, I should say, sorry.

How many people do I employ altogether? Let's have a think that, what is my bar model going to look like for this? Well, I don't know how many altogether, but I do know in my shops, I employ 1,368 people.

And I know that in my baking factory, I employed 2,461 people.

But I don't know in total how many I employ.

So I need to do some it's probably important, I know that.

So, to work that out, I'm going to add them together 'cause I don't have that whole value here.

I don't know the whole value.

So I need to add these values together to give me that whole, my two parts.

So we're going to start with our ones.

Eight add one is equal to nine, six add six is equal to 12.

Remember I cannot write 12 into the one column, so I need to regroup and put one of my tens in my hundreds column because I actually have 12, tens, and the two tens remaining in my tens column.

Then I can do three add four, which is seven.

Don't forget to add that one, gives me eight and then I can do one add two is equal to three.

So here is my answer.

Again, we could check our answer using that inverse operations.

So let's see, going to take my whole and I'm going to subtract one of the parts to see if I get my other part as my answer.

So nine subtract eight is equal to one.

Two subtract six, I can't do that without regrouping.

So my eight hundreds becomes seven hundreds and I get 10, tens.

12 tens, subtract six tens, gives me six tens.

Seven, subtract three.

Remember those are hundreds, gives me four and three subtract one gives me two which is thousands, 'cause it's in the thousands columns.

Is it the same number as my other part? Absolutely it is.

So I know I haven't gone terribly wrong.

Okay then if you're feeling confident once I've revealed this, you can pause the video.

What's this bar model going to look like.

Mrs Crane's bakery made 1,269 pounds on Friday.

The total amount of money she had made by Sunday was 3,643 pounds.

How much money did she make on Saturday and Sunday? Okay so, if you're feeling really confident, I'd like you to pause the video now, to have a go at drawing this bar model and if you're feeling really confident, you can challenge yourself to solve the equation.

If you're not, then we're going to reveal it together now.

So here's my bar model.

You can see here, this is the total amount that I had made across Friday, Saturday and Sunday.

Here you can see this was the total amount I made on Friday, but we don't know the amount of money that was made on Saturday and Sunday.

That's the question mark here.

That's my missing value here.

So to work that out, I'm just going to move myself slightly so that you can see the full question.

To work out, I need to take my total amount, my whole 3,643, I'm subtracting one of the parts.

The part that I know, which is the amount that I've made by Friday.

I don't know part that tells me how much was made on Saturday and Sunday.

So start off, oh, what do I notice? As soon as I look at my ones column, what do you notice? I noticed that the value in the number I'm taking away from the columns, that the number of below it, sorry.

The nine is greater than the three, which tells me I need to do something.

What do I need to do? Fantastic, I need to do some regrouping.

So I'm going to regroup on my four, tens is going to become three, tens.

So I'm going to get 10 ones to join my three ones in my ones column.

13, subtract nine.

Can I do that? Yes, I can.

And it's going to leave me with an answer of four.

Three subtract six, oh, I don't know if it's okay.

Again, the number I'm taking away from is smaller than the number I'm taking away.

It's wanting to do some more regrouping.

So my six hundreds are going to become five hundreds, I'm now going to have 10 tens to join my three tens.

To give me 13 tens.

Now I can do 13, take away six and it gives me seven.

Five hundreds take away two hundreds, gives me three and 3000 take away 1000 gives me two.

So my number, how much money that I made on Saturday and Sunday has to be 2,374.

Again, we could check our answer using the inverse.

Let me move myself back up so that we don't have to worry too much about the question for this part here.

So using my inverse, I'm going to add both of my parts together to see if I can make my whole.

So four add nine is equal to 13.

I have to remember that.

I need to regroup that and show that by putting that one in the tens column.

Seven add six, add one takes me to 14.

Again, I'm going to show that regrouping here.

Three add two, add one is equal six and two add one is equal to three.

So my answer 3,643 is the same as the total amount.

So I know I accurately found out how much money I made on Saturday and Sunday.

I made 2,374 pounds on Saturday and Sunday.

So it's now time for your task today.

It's going to be your turn, having a go at representing, a word problem.

Going to hide myself again, so I explain this to you.

So today's task, I would like you to represent each problem.

So this four problems here, using a bar model, and then I'd like you to calculate the solution.

Remember label the values, that you have been given.

So using that bar model, mark on if you've got a question mark.

If you know the part, if you know both parts or if you know the whole.

Your four questions are on the screen there.

Please pause your video now to complete your task.

Don't forget to resume it once you're finished, so we can go through today's answers together.

Okay then, welcome back.

I'm going to put myself back on the screens, so you can see me as we go through the answers.

Okay, we're going to start off with the question.

A Parisian bakery baked 2,645 baguettes in the morning and has sold 1,927 by lunch time.

How many baguettes were left after lunch time? So we know that total amount so my bar model, I've marked on my total is 2,645.

I know one of my parts.

I know how many were sold in the morning and I know 1,927 were.

The part I don't know is how many were sold in the afternoon.

So I want to take this part away from my whole if we need this answer.

So, five subtract seven.

Can I do that? No, I can't.

I need to do some regrouping.

So my four hundreds, not hundreds, sorry, being carried away with myself.

My four tens become three tens and I have 15 ones.

Subtract seven one's gives me eight ones.

Three tens take away two tens gives me one tens.

Oh six hundreds take away nine hundreds, can I do that without getting myself into a bit of a model and using negative numbers? Nope, I can't.

So I need to regroup 1000, which leaves me with 1010 hundreds.

So I now have 16 hundreds take away nine hundreds, which leaves me with seven hundreds.

1000 take away 1000 is zero.

So my answer is 718.

So only 718 baguettes were left for the afternoon.

Question two then.

In the morning, there were some people at the Pompidou centre.

During an exhibition, 7,364 people visited.

The centre could hold a maximum of 8,000 visitors a day.

How many more people could be allowed in? Or could have been allowed in.

So I know that whole value.

I know that they could only allow 8,000 visitors each day.

And I know that during one exhibition, there were 7,364 people who were allowed into the exhibition.

What I don't know is how many more they could have let me in.

Maybe they could have let me in, if I'd been queuing at the Pompidou centre, but I haven't, they could have let in.

So let's work that out by taking away 7,364 from 8,000.

Now, an appropriate and efficient strategy for this would be to use counting on.

So counting onto this one and I got to the answer, 636.

Next question then.

The Louvre Museum had 4,583 visitors on Monday morning and 5,379 visitors on Monday afternoon.

What was the total number of visitors on Monday? So I've got one part and I've got the other part, but I don't have that whole amount at the moment.

So to answer this equation, I need to add together these two values to give me my whole.

So I'm going to start with our ones.

Three add nine is equal to 12.

Remember we need to record that like so, so we don't forget to add the regrouped one.

Eight add seven, add one is equal to 16.

I do that by doing eight add eight, 'cause I've regrouped my one into my seven, that to mean eight.

We could do it really quickly then.

Five add three is eight plus one is nine and four and five is also nine.

So I know my total whole value of visitors that we could have had would have been 9,962.

Last question then is the Louvre has a mix of paintings and sculptures.

There are 6,800 not 800, 6,482 pieces of artwork altogether.

If 2,726, are sculptors, how many are paintings? So I know how many pieces of artwork there are altogether.

And I know that this amount here tells me how many sculptures there are, what I don't know is how many paintings there are.

So I don't know about one other part.

So I'm going to do some subtracting.

So I'm going to do 6,482 subtract 2,726.

We're going to start with my ones column.

Can I do that without regrouping? No, I can't.

So I'm going to regroup, one tens to leave with seven tens, and 12 ones, 12 take away six gives me six.

Seven take away two gives me five.

Can I do my hundreds column? Can I do it? Can I solve that without regrouping? I have to regroup.

So I'm going to regroup 1000 in the five thousands for 10 hundreds, to give me 1,400.

14 take away seven is equal to seven.

Five take away two is equal to three.

So my answer, 3,756 were paintings.

If you'd like to please ask your parent or carer to share your work today on Twitter, by tagging at Oak National and using the hashtag learn with Oak.

Fantastic work today, I've been really, really impressed.

Now don't forget to go and complete that quiz to show off all the amazing work you're doing.

And don't forget that when you're using these columns, there are regroup numbers that you'll need to add in.

Fantastic, hopefully I'll see you again soon for some more Maths.

Thank you and goodbye.