# Lesson video

In progress...

Hello everyone.

And welcome to maths with Ms.Dobrowolski.

In today's lesson, we'll be comparing the mass of objects in kilogrammes.

Let's have a look at today's lesson agenda.

First, we'll be learning about one kilogramme.

Then we'll be reading scales in kilogrammes.

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.

Let's get started.

So at the post office the parcels need to be weighed before they can be sent.

Do you know why? That's because the greater the weight of the parcel, the more money that needs to be paid in order to send it.

Can you think of any other jobs where something might need to be weighed? I can think of when you go to the doctor's office, the doctor might weigh you.

Or maybe a construction worker might need to weigh the bricks or the other materials that they're using to build a house.

So there's lots of other jobs that require things to be weighed.

Now, one kilogramme is a unit of mass that is often used to weigh objects.

One kilogramme.

Good.

Let's try that again.

Kilogramme.

Good.

And when we record kilogrammes we always write the letters, kg.

And that's because the word kilogramme, it's a long word, so we can shorten it to kg.

And when you see kg, you know, Oh, this is in kilogrammes.

So here you can see the scales are perfectly balanced, which means that the objects on each side have an equal weight.

One kilogramme is equal to one kilogramme.

Now, there are loads of items in your house that may weigh one kilogramme.

For example, you might have some mixed vegetables or some pasta or some other items. Kilogrammes are all over the place.

If you do look at some items in your house, you can look at the back of the item and you might see 1kg, or a different mass on there.

So, is the letter heavier than, lighter than, or as heavy as one kilogramme? We can see that the letter is floating up and one kilogramme is sinking down.

This means that the letter is lighter than one kilogramme.

Lighter than.

The letter is lighter than one kilogramme.

Good job.

What about the handbag? Is the handbag heavier than, lighter than, or as heavy as one kilogramme? Well, the handbag is sinking all the way down and one kilogramme is going up.

So that means the handbag is heavier than one kilogramme.

Heavier than.

The handbag is heavier than one kilogramme.

Good job.

Okay.

Let's have a look at the parcel.

Is the parcel heavier than lighter than, or as heavy as one kilogramme? Well, I can see here that neither the parcel and neither the kilogramme, are sinking down or moving up.

They're perfectly balanced.

So that means the parcel is as heavy as one kilogramme.

As heavy.

The parcel is as heavy as one kilogramme.

Great job.

Now what I would like for you to do is look for some items around your house that weigh one kilogramme.

So for example, I found this really big bag of walnuts in my home.

And I looked all over the package and I saw that it says one kilogramme.

So that means I can see this is equal to one kilogramme because it says one kilogramme on the package.

Now, when you look for items around your house, you might find the weight on the front or on the back.

So what you have to look for it.

So pause the video now and check.

Can you find some items in your home that are equal to one kilogramme? Make sure you ask an adult for help, especially if you're getting anything heavy or anything off the top shelf.

So pause the video now and go find some items. Good luck.

Super job, everyone.

We can read the mass of object by looking at the number the needle rests on the scale.

So here's the needle and it's resting on three.

That must mean the newspapers are three kilogrammes.

They are heavier than one kilogramme.

Now let's look at the weight of the sack.

So again, we look at where the needle is resting and it looks like it's resting on nine or pointing to nine kilogrammes.

So the sack is nine kilogrammes.

The sack is heavier than the newspapers.

The sack is nine kilogrammes and the newspapers are only three kilogrammes.

So the sack is heavier than the newspapers.

Now let's refresh, is the handbag heavier than, lighter than, or as heavy as one kilogramme? You tell me.

That's right.

It is heavier than, the handbag is heavier than one kilogramme.

So let's see how much does the hand bag weigh? Where is the needle pointing to? That's right.

Two kilogrammes.

So the handbag weighs two kilogrammes.

And the parcel, heavier than lighter than, or as heavy as one kilogramme.

You tell me.

That's right.

The parcel is as heavy as one kilogramme.

So when we go to weigh it, we can see that the needle is pointing to one and it's measured in kilogrammes.

So it is as heavy as one kilogramme.

Now, let's have a look.

I can see that the parcel weighs one kilogramme and the newspapers weigh three kilogrammes.

I can see that the parcel is less than the newspapers.

So I use the less than symbol when comparing these items. The parcel is less than the newspapers.

Let's order these from lightest to heaviest.

Which of these are lightest? The parcel for four kilogrammes? The parcel that weighs one kilogramme? The three kilogramme newspapers? Or the two kilogramme handbag? So the lightest object is it the parcel that only weighs one kilogramme.

Now.

The handbag that weighs two kilogrammes is heavier than the parcel.

So that's continue on.

We had the parcel for one kilogramme, then the handbag for two kilogrammes, what comes next? The other parcel or the newspaper? That's right.

The newspapers are heavier than the handbag and the parcel, but they're not the heaviest.

The heaviest object is the parcel for four kilogrammes.

So we went from one kilogramme, two kilogrammes, three kilogrammes, four kilogrammes.

We went from lightest to heaviest objects.

Now, which of these is heavier? The newspapers are three kilogrammes and the sack is nine kilogrammes.

So I know that the sack is heavier.

But how much heavier is the sack than the newspapers? We can use a bar model to help us.

So I know that the sack has a weight of nine kilogrammes and the newspaper only has a weight of three kilogrammes.

The difference between the two is what I'm looking for.

I know nine minus three is equal to six.

So the sack is six kilogrammes heavier than the newspaper.

What is the total mass of the newspapers and sack? Now, if I want to find the total mass, I can use a bar model to help me.

So three kilogrammes and nine kilogrammes, the total mass, that means I need to add them together.

Three plus nine is equal to 12.

So the total mass of the newspapers and the sack is 12 kilogrammes.

Let's have a look.

The mass of the book is one kilogramme.

The mass of the sack is nine kilogrammes.

Which is lighter? That's right.

The book is lighter than the sack.

How much lighter is the book than the sack? Well, let's take a look.

Again, I want to know the difference.

So if I know that the book is one kilogramme and the sack is nine kilogrammes, I need to find the difference between nine and one, this missing part.

So nine minus one is equal to eight.

That must mean the book is eight kilogrammes lighter than the sack.

What is the total mass of the book and sack? Well, if I want to find the total mass, I can add my parts together.

And my parts are nine kilogrammes and one kilogramme.

nine plus one is equal to 10.

So the total mass is 10 kilogrammes.

Great.

What you need to do is answer the questions.

So I'll do the first one.

The mass of the suitcase is.

I'm going to look at the scale, that says nine kilogrammes.

So I fill in nine.

Good luck.

Super job, everyone.

So here we can see that the mass of the apples is two kilogrammes.

The sugar is one kilogramme.

And here it was asking you to fill in an item that was greater.

So here I said, the weight of the suitcase is greater than the weight of the sugar, because the suitcase was nine and the sugar is only one.

You could have also said the weight of the suitcase is greater than the mass of the apples.

Or you could have said the weight of the apples was greater than the weight of the sugar.

Now here was asking you to fill in the weight that was less than another weight.

So you could say the weight of the sugar is less than the weight of the apples.

Or you could have also said the weight of the sugar was less than the weight of the suitcase, or that the weight of the apples was less than the weight of the suitcase or the weight of the sugar was less than the weight of the suitcase.

The suitcase was seven kilogrammes heavier than the apples.

The sugar is one kilogramme lighter than the apples, and the total weight of the suitcase, apple and sugar was 12 kilogrammes after I added all of these together.

Super work, everyone.