Lesson video

Hello everyone and welcome to maths with Ms. Dobrowolski.

Today we'll be consolidating our knowledge of mass through investigations.

Let's have a look at our lesson agenda.

So first we'll be looking at interpreting scales, then we'll be investigating like detectives, then you'll have your talk task and finally you'll be ready for your independent task.

For this lesson you will need a pencil and notebook.

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

Super.

So, I have three scales here.

What's the same? What's different? Pause the video and write down some answers, have a think.

Super.

So as you can see, what's the same is all the scales are doing the same job, right? They all are weighing our items. But what's different is that all these scales are giving us the mass in different ways.

So here we have it digitally, the weight of this water bottle or its mass is 158 grammes.

Here, this scale was in kilogrammes so the weight of this parcel's one kilogramme.

And then here as well we also had kilogrammes.

So the weight of this sack was nine kilogrammes.

So, even though all these scales are giving us answers different ways, in grammes or in kilogrammes, digitally or not, they're still giving us the mass of something.

So that part is the same.

Now, does anyone know how many grammes are equal to one kilogramme? Do you know? It is 1,000 grammes.

I would need 1,000 grammes to equal one kilogramme.

So if I know that 1,000 grammes are needed to equal one kilogramme, how many grammes are equal to two kilogrammes? That's right, it is 2,000.

So one kilogramme is equal to 1,000 grammes, two kilogrammes are equal to 2,000 grammes, so then three kilogrammes must be equal to 3,000 grammes.

Super.

Now, let's do a little bit of investigating.

So we're going to have to be detectives for this one.

So this is Bob, and Bob is travelling on holiday, but his airline only allows him to bring five kilogrammes in his luggage.

He can't bring more than that or they won't let him on the flight.

So what items can he bring in his suitcase? Well, what we need to do is figure out the different combinations that Bob can bring.

I like to work systematically which means to work in order, one by one, because if I'm just randomly combining different items, I forget really quickly what items I've already tried combining.

So what I'm going to do is I'm going to make myself a table, and I'm going to write down all the different combinations that work.

First I'm going to start with the laptop, so I'm going to try combining the laptop with other items. Okay, I know the laptop has a weight of three kilogrammes, and Bob can only bring up to five.

If I go over five kilogrammes, Bob can't bring that combination of items. Okay, so first I combined the laptop and the book.

Three kilogrammes plus one kilogramme was equal to four kilogrammes.

Then I tried combining the laptop and the shoes.

But then I realised three plus four, that's equal to seven, so he can't bring the laptop and the shoes, that's too much.

The mass of those two items is more than five kilogrammes.

So then I tried the laptop, the book and the mask, and that was three kilogrammes plus one kilogramme plus one kilogramme which is equal to five kilogrammes.

So that was fine, Bob could bring the laptop, the book and the mask.

Then I also realised, oh, Bob could also just bring the laptop and the umbrella because three kilogrammes plus two kilogrammes is equal to five kilogrammes.

Or Bob could also just bring the laptop and the mask because that was only equal to four kilogrammes.

So I've exhausted all the different combinations that I could make with the laptop.

So now that I've done that, I'll go on to the next item which was the shoes.

So, the shoes were four kilogrammes and the book is only one kilogramme.

So that means four kilogrammes plus one kilogramme is equal to five kilogrammes, so that was fine.

Again, I couldn't combine the shoes and the laptop because that would be too much, I already tried that combination and I know it was equal to seven kilogrammes which was too much.

I also tried the shoes and the umbrella, but four kilogrammes plus two kilogrammes is equal to six kilogrammes, so that combination won't work.

So then I tried the shoes and the mask.

Four kilogrammes plus one kilogramme is equal to five kilogrammes.

And then I realise I have exhausted all my options for the shoes.

So I moved on to the book.

So I combined the book, the mask and the umbrella.

One kilogramme plus one kilogramme plus two kilogrammes is equal to four kilogrammes.

So, then I realised I could also just take the book and the mask because one kilogramme and one kilogramme are equal to two kilogrammes.

And at that point I had already exhausted, I had no idea I had one more combination which was the book and the umbrella.

One kilogramme plus two kilogrammes is equal to three kilogrammes.

And then last but not least I could also combine the mask and the umbrella, one kilogramme plus two kilogrammes is equal to three kilogrammes.

And I know that I have exhausted all the options, I've thought of all the ways because I work systematically.

I started with the laptop then I went to the shoes and then I went to the book.

And I thought of all the different combinations.

So, what I'd like for you to do for your talk task is help Jenny.

Jenny is travelling on holiday but her airline only allows her to bring 10 kilogrammes in her luggage.

What items can she bring in her suitcase? Well, the same that I did with Bob is what you're going to do for Jenny.

You're going to write down all the possible combinations, and I'd really like for you to work systematically which means in order.

So maybe you want to start with the laptop and try all the different combinations you can make with the laptop.

And then move on to the boots and so on and so forth.

So, your turn.

Pause the video, make all the different combinations that you can, resume the video when you're ready to go over the options.

Good luck.

Super.

So, Jenny had a couple of different options because she could take up to 10 kilogrammes.

So, you could have combined the laptop and the boots, the laptop and the book, the laptop, the books and the shoes, the boots and the shoes, the boots and the book, the book and the shoes, the book and the ball, and the ball plus the shoes.

Good job, everyone.

So, last but not least I want you to try this one more time, and this time for your independent task I want you to help Sarah.

So Sarah is travelling on holiday, but her airline only allows her to bring 20 kilogrammes in her luggage.

What items can she bring in her suitcase? So Sarah can take up to 20 kilogrammes which is significantly more than what Jenny and Bob can take.

If I were to solve this, I would make myself a table just like this so I can work systematically when I'm figuring out all the different combinations.

You can make a table as well, but if you have a different way of working systematically, that's fine, you might think of a better way than I did.

So, pause the video, try and figure out all of the different possible combinations, resume the video when you're ready to go over the answers.

Good luck.

Super.

But here are all the different combinations.

She could have taken the laptop and the boots, the laptop, the boots and the umbrella, the laptop and the paint, the laptop and the umbrella, the laptop, the paint and the umbrella, the boots and the paint, the boots and the umbrella or the paints and the umbrella.

I'd be really curious to see how you work systematically and what combinations you were able to come up with.

So, if you'd like to, please ask your parent or carer to share your work on Instagram, Facebook or Twitter tagging @OakNational and #LearnwithOak.

As always, don't forget to complete your final quiz and I really hope to see you in future lessons, bye.