Lesson video

Hello everyone and welcome to maths with Ms. Dobrowolski.

In this unit, we're studying money and in today's lesson, we'll be developing our problem solving skills, when it comes to questions with money.

In today's lesson agenda, we'll first look at how to approach a problem, then we'll complete our talk task followed by our independent task, and then you'll be ready for your final quiz.

For this lesson, you will need a pencil and a notebook.

If you don't have these items, pause the video now and go get them resume when you're ready.

So deciding how to approach a problem.

So here in the corner, we have Emily and Emily says I have 10 Ps to spend.

What could I buy if I spent all my money? Well, when I approach a math problem, the first thing I think about is what information do I already know? And I know quite a bit from looking at the picture and listening to Emily, for example, I know that my whole is 10 P and that's because Emily has said I have 10 P to spend.

So I know that the total amount is going to be 10 P.

I also know the cost of each item.

Each jelly bean is two P.

Each candy is three P each lolly is five P and each chocolate bar is seven P.

Once I've looked at what I know, I then need to think about what do I need to know? What's some information I don't yet have? and I need to know my parts to make my whole.

See, I don't actually know how many parts I have, because I don't know what Emily has spent her money on yet.

That's what I'm going to figure out.

And finally, I need to think what problem solving strategies that might help us? Well, there's two I really like for this question.

The first strategy I like to use is to work systematically.

And that means working in order one by one so I don't miss anything out.

The second strategy I really like is called trial and improvement, which means testing out answers and see if they work.

And I'll explain what both of those mean because we're going to need them for our talk task.

So again, Emily has gone to the shop She's gone to Morrisons and she has 10 P to spend.

What could she possibly buy? You see there's many answers to this question because there's many combinations of different sweets that she could try.

So when I work systematically, I think, okay first we could try starting with the jelly beans.

So I know that one jelly bean costs two P.

So I can say two P plus three P is equal to five P.

I still haven't made it to 10, so I can buy something else or Emily can buy something else.

If I already have two P plus three P equal to five P how much more do I need to make 10 P Oh five and five make 10 so I can get a lolly or Emily can get a lolly.

So if Emily buys a jelly bean, a candy and a lolly, that will be two P plus three P plus five P, which is equal to 10 P.

That's one possible combination.

Now it is your turn to try and figure out what other combinations of sweets she could've purchased.

Remember she only has 10 P and she must spend all of the 10 P.

So as you're working out the different possibilities, make sure that whatever Emily is buying always equals 10 P.

Pause the video now try and figure out some other combinations and when you're ready, resume the video so we can compare answers.

Great.

So did you find all the possibilities? Let's see, let's look at the ones I found.

So I know I said jelly beans and a candy and a lolly.

I also found that Emily could purchase a candy and a chocolate bar because three plus seven is equal to 10.

And she also could have purchased two lollies that would have cost five P plus five P, which is equal to 10 P.

I know I'm sure of my answer because I worked really systematically.

I first tried combining the jelly beans with all the different types of candies to see if I could make it equal to 10.

Then I tried combining all the candy with all of the other different sweets to see if I could make 10.

Then I tried with the lolly, then I tried with the chocolate bar.

So I know I'm sure.

And that's the really great thing about working systematically.

You don't leave anything out.

Now, you might've done this a different way, and I'd be really curious to hear about how you did it and whether or not you followed a table like I did that really helps me.

Let's move on to our independent tasks.

So Emily and her mom went to buy some sweets too.

They each had 20 P to spent and they both spent all of their money.

So remember when we develop our problem solving skills and when we approach a problem, we have to ask ourselves some questions.

What information do you know? What do you need to know? And what problem solving strategies might help you? So let's see, they each had 20 P to spend and they both spent all of their money.

Emily bought at least one kind of each sweet.

Which one did she have two of? So remember what information do you know? What do you need to know? And what problem solving strategies might help you? Pause the video now complete your independent task, and when you're ready, you can resume the video and we can compare answers.

If you're really not sure about what to do, go back to the top task and look at the table I made, you can make a similar table here for this problem as well.

So pause the video and I'll see you for the answers.

Great well done everyone.

So when I worked through this problem, I know that my whole was 20 P because it said they each had 20 P.

So I know Emily has 20 P.

I also know I will have five parts and that's because Emily bought at least one kind of each sweet.

So that's one, two, three, four.

Which one did she have two of? So I know Emily definitely bought at least four and then a fifth one, because she had at least two of one of them.

So that's five parts.

Okay.

My whole is 20 and I have five parts.

This is the trial and improvement method I came up with.

First I said to myself, okay "Well, what if she purchased two of the jellybeans?" Two plus two is four plus three is seven, seven plus five is 12 and 12 plus seven is equal to 19.

Is that equal to 20? Nope so that didn't work.

Then I tried with two candies.

Three plus three is six, six plus two is eight, eight plus five is 13 and 13 plus seven is 20 P.

Great that works.

So she could have bought two candies, one jelly bean, one lollipop, and one chocolate bar.

Because when I added those numbers up, they were equal to 20.

Then I tried with two lollies.

Five plus five is 10 plus two is 12, plus three is 15 and 15 plus seven is equal to 22, which is not equal to 20.

So that did not work.

I then also tried with two chocolate bars.

seven plus seven is 14, 14 plus five is 19, 19 plus three is 22 and 22 plus two is 24, which is also not equal to 20.

So the only combination that worked is if Emily bought two candies.

Two of these yellow candies.

Let's move on to our second independent task.

Again, Emily and her mom went to buy some sweets, too.

They each had 20 P to spend and they both spent all of their money.

This time Emily's mom spent her money on just one kind of sweet, but she does not like jelly beans.

So which sweets did she buy? Remember when we're approaching a problem, we have to think about what information do we know? What information do we need to know? And what problem solving strategies might help? Now is your turn to complete the task.

Make sure to pause the video and resume when you're ready so we can compare answers.

Now, there were many different ways to complete this problem.

I've done it one way, but if you've done it in another, that's completely fine.

So let's have a look.

I know that my whole is 20 P because that's how much Emily's mom had to spend and she spent all of her money.

I also know that I have a part, but I don't know how many parts I have because Emily's mom could've bought more than one sweet.

Because my whole has to be 20.

I do know that she doesn't like jelly beans, so when I began working systematically on this problem, I did not include jellybeans because I know Emily's mom didn't buy those.

So first I started off with candies and I tried to add up candies so that it would be equal to 20.

When I added six candies, three plus three plus three plus three plus three plus three, my total was 18, which is not equal to 20.

So I tried adding a seventh candy.

Now I added another candy.

So I'm adding three seven times, which is equal to 21.

That does not work.

That would never have equaled 20 P.

So I moved on to lollies and I said, "Okay, can I add five enough times to make 20?" Well, if I add five plus five is 10, 10 plus five is 15 and 15 plus five is 20.

So Emily's mom could have bought four lollies.

I then tried chocolate bars.

Seven plus seven was equal to 14, so that wouldn't have worked.

But when I tried adding a third chocolate bar that was equal to 21.

So Emily's mom could not have purchased chocolate bars because it never would have equal 20.

So I know that the only sweet Emily's mom could've bought was a bunch of lollies.

Four to be exact.

Well done everyone.

If you'd like to, you can share your work with Oak National by asking your parents or carer to share your work on Instagram, Facebook or Twitter, tagging @OakNational and #LearnwithOak.

Don't forget to complete your final quiz before you go.

That was some really good thinking all of you did today.

I was really impressed.

It was really nice to see you and I hope to see you for future lessons.

Bye.