Lesson video

Hello, everybody.

My name is Mrs. Johnson.

I am so happy to be here today to help you with some of your maths learning.

I hope you're ready to work hard and have lots of fun as we learn new things.

Let's have a look at what we're going to be learning about today.

This lesson is called "Mass Can Be Measured in Grammes and Kilogrammes." It comes from the unit Sense of Measure.

By the end of this lesson, you will be able to describe the mass of a kilogramme and a gramme, and you will be able to choose which unit might be best to measure different masses.

Don't worry if you're not sure what mass means at the moment, because we are going to have a look at this together.

There are some keywords that we need to practise so that you are ready to start your learning.

I will say them first.

And then it will be your turn.

Ready? My turn: mass.

Your turn.

My turn: gramme.

Your turn.

My turn: kilogramme.

Your turn.

Well done.

Listen out for those words today because they are really going to help you with what you are learning about.

There are going to be two parts to this lesson.

To begin with, you're going to think about this question: what are grammes and kilogrammes? And then in a little while, you are going to learn about measuring mass.

Let's get started by finding out what are grammes and kilogrammes.

There are two friends who are going to help us in this lesson today.

Their names are Sofia and Jacob.

Listen carefully to the things that Sofia and Jacob have to tell you, because they are going to be really important for your learning today.

Sofia wonders, "What are the heaviest things you can think of?" Ooh, what really heavy things can you think of? Jacob has some ideas.

He was thinking of an elephant, a car, an aeroplane.

Those things would be very heavy, wouldn't they? I wonder what else you thought of.

Now Sofia wonders, "What are the lightest things you can think of?" Hmm.

Jacob's got some ideas again.

Let's see what he's thought of this time.

I wonder if they'll be the same things that you've thought of: a feather, a five-pence coin, a balloon.

Hmm, those things are very light, aren't they? I wonder what else you thought of.

When you think about how heavy something is, you are thinking about its mass.

Sofia says she could use objects, such as building blocks, to measure the mass of this pen so to measure how heavy it is.

She can put it in one of the buckets on the balance.

And then in the other bucket, she's going to start adding blocks, and she's going to keep adding blocks until it balances like this.

When the two sides balance the masses are equal.

That means that the mass of this pen is equal to the mass of these six building blocks.

You could say that the pen is as heavy as six blocks.

You can also measure mass using standard units.

Sofia says that, when she measures length, she uses the standard units centimetre and metre.

I wonder what the standard units will be for measuring mass.

There are lots of different standard units for measuring mass.

Two of the standard units that are often used for measuring mass are called grammes and kilogrammes.

That's what you are going to learn more about today.

Sofia has noticed that, on her packet of sweets, it says that it has a mass of 30 grammes.

I wonder if you've ever noticed any grammes or any kilogrammes on your packets of food that you have.

Jacob wonders, "How heavy is one gramme?" Let's have a look at that now.

These objects all have a mass of about one gramme.

That means they are all as heavy as about one gramme: a 10-pound note, a paperclip, a raisin.

Sofia says, "I think one gramme would feel very light if I held it in my hand." Can you imagine holding one raisin or one paperclip or one 10-pound note in your hand? It would feel very light, wouldn't it? Jacob wonders if one kilogramme is going to be heavier or lighter than one gramme.

What do you think? Let's have a look.

These objects all have a mass of about one kilogramme: a bunch of bananas, an adult's pair of trainers, a laptop.

Sofia thinks that one kilogramme would feel quite heavy if she held it in her hand.

Maybe later, you might be able to find an adult pair of trainers or a bunch of bananas or a laptop and carefully hold it so that you know what it feels like to hold one kilogramme in your hand.

"One kilogramme is definitely heavier than one gramme," Jacob says.

If we know that a raisin has a mass of about one gramme, we know that's not as heavy as a bunch of bananas, which has a mass of one kilogramme, so a kilogramme is heavier than a gramme.

Let's check that you understand the mass of a gramme and a kilogramme.

Can you match each object to its mass? You've got a cake, a drawing pin, a balloon, and a rabbit.

You need to decide if each one would be about one gramme or about one kilogramme.

Pause the video, and have a go now.

Well done.

Let's have a look.

The cake would be about one kilogramme.

The pin is about one gramme.

The balloon is about one gramme, and the rabbit is about one kilogramme.

Now you're going to practise thinking about grammes and kilogrammes.

These objects all have a mass of about one gramme: a pin, a 10-pound note, a raisin, and paperclip.

You need to have a look around you.

See if you can find any more items that could have a mass of about one gramme.

You need to draw or write as many different objects as you can.

Once you've done that, you're going to have a go at completing this table.

This time, you need to look around you to try and find things that would be heavier than one kilogramme and things that would be lighter than one kilogramme.

You might want to pick them up and feel their mass.

Feel how heavy they are.

Remember that the mass of a laptop or a bunch of bananas or an adult's pair of trainers is about one kilogramme.

Use that to help you decide if you think it would be heavier than one kilogramme or lighter than one kilogramme.

Pause the video, and have a go at that now.

Well done.

I wonder what you found when you were looking for objects that could have a mass of about one gramme.

These're the things that Sofia found.

She's chosen a pen lid, a small building block, a straw, and a seed.

Each of these items wouldn't feel heavy at all if you held it in your hand.

Sofia was trying to remember that it needs to be about one gramme, which is about the same mass as a paperclip or a raisin, so it should feel, when you hold it in your hand, about the same as it feels when you hold a paperclip or a raisin or, perhaps, a 10-pound note.

Let's have a look at how Jacob has completed his table for the second question.

For heavier than one kilogramme, he has written, "Chair, table, cupboard, box of books, tray of cubes, and my teacher's bag." In the lighter-than-one-kilogram, he found a pen, a pencil, a reading book, a glue stick, a water bottle, and a ruler.

I wonder if any of these are the same as the objects that you found.

What other masses did you find? Did you pick them up, think about how heavy they feel and whether they might feel heavier than a laptop or a bunch of bananas or whether they would feel lighter? Well done if you did, because that's a really good way to think about one kilogramme and how heavy that is.

Now it's time for the second part of the lesson, and you are going to be thinking about measuring mass.

We know that there are at least two different units of measure that we can use for measuring mass: grammes and kilogrammes.

Sofia is wondering, "Why is there more than one unit of measure? Why don't we always just measure in grammes?" I wonder if you can think of a reason why we might need grammes and kilogrammes.

Why don't we just measure everything in grammes? Let's have a look.

Jacob wants to look again at how heavy one gramme and one kilogramme are.

One gramme is about the same mass as a 10-pound note, paperclip, or a raisin.

One kilogramme is about the same mass as an adult's pair of trainers, bunch of bananas, or a laptop.

Jacob knows, from this, that a gramme is much lighter than a kilogramme.

So maybe, we have different units of measure so that you can choose which units will be most helpful for the mass that you are measuring.

Kilogrammes are really helpful when you want to measure a heavier mass, for example, a person or a bag of potatoes.

It is possible to measure heavier masses in grammes, but it could be more difficult and not as efficient as measuring in kilogrammes, because there would be a lot of grammes when you needed to measure the mass of something heavier.

Sofia is thinking, "If I wanted to measure something lighter, I could choose grammes, but if I wanted to measure something heavier, I could choose kilogrammes." That's why there is more than one unit of measure.

Let's check that you can think carefully about which unit of measure might be sensible to choose.

True or false? If you wanted to measure the mass of an apple, it is sensible to choose to measure in kilogrammes.

Do you think this is true or false? And can you think of a reason why? Pause the video, and have a think now.

Well done for thinking carefully.

This is false.

Remember one kilogramme is about as heavy as a bunch of bananas.

The mass of an apple is likely to be lighter than the mass of a bunch of bananas, so it would be more helpful to choose grammes to measure an apple, rather than kilogrammes.

Well done if that's what you were thinking, too.

Now, Jacob and Sofia are going to play a game.

Jacob is going to show two measurements, and Sofia has to say which one she thinks is correct.

Sofia is remembering what she's learnt so far, because that's going to help her with Jacob's game.

She can remember that one kilogramme is about as heavy as a laptop and that one gramme is about as heavy as a paperclip.

Let's see how they get on playing Jacob's game.

Jacob says, "Do you think the mass of a crayon is about six kilogrammes or six grammes?" Hmm, Sofia's having a think.

Would it be six kilogrammes or six grammes? She's imagining holding a crayon in her hand, thinking about how heavy it would feel.

She says, "I choose six grammes.

Six kilogrammes is far too heavy for a crayon." Jacob says, "You are correct.

Well done." Let's see what Jacob gives Sofia next: "Do you think the mass of my chair is about eight kilogrammes or eight grammes?" Sofia's having a think again.

Would a chair be as heavy as eight kilogrammes or eight grammes? Sofia says, "I pick eight kilogrammes.

Eight grammes is far too light for a chair." Remember that one gramme is about the same as one raisin.

Can you imagine holding eight raisins in your hand? Would that feel as heavy as a chair? Definitely not.

That's far too light, so it must be eight kilogrammes, and Jacob says, "Correct again.

You really understand kilogrammes and grammes now.

Well done." Let's check if you understand kilogrammes and grammes.

What do you think is the missing measurement in this sentence: "A paintbrush could have a mass of"? Hmm, could it be 26 grammes or 26 kilogrammes? Pause the video, and have a think.

Let's have a look.

A paintbrush could have a mass of 26 grammes.

Remember the mass of a laptop is about the same as one kilogramme, and it's not very likely that a paintbrush would be heavier than a laptop, so it's more sensible to choose 26 grammes than 26 kilogrammes.

Well done if you said 26 grammes.

Now, Jacob and Sofia are feeling confident that they know when they should choose grammes and when they should choose kilogrammes to measure something, but Sofia wants to know how could we actually measure mass and find out how heavy something is.

We're going to have a look at that now.

I wonder if you've got any ideas.

Let's see.

When you want to measure the mass of something, you can use a scale.

Here is a scale that you might use to measure mass.

Some scales, like this one, count from left to right in ones.

Jacob could use this scale to find the mass of different objects.

He needs to place the object that he wants to measure on the scale.

And then he can read that the mass of this brick is two kilogrammes.

Now, Jacob is going to use a different scale.

Can you see what's different on this scale? This time, this scale can measure in grammes, and it counts in fives from left to right.

Jacob can place the object that he wants to measure, and he can see that the mass of these scissors is 35 grammes.

Now, Jacob's going to use a different type of scale.

This scale reads from the bottom to the top.

It measures in grammes, and it counts up in tens.

Jacob can place the object that he wants to measure, and he can see that the mass of this banana is 80 grammes.

Some scales, like this one, can be read around in a circle in a clockwise direction.

This scale measures in kilogrammes, and it counts up in twos.

Sofia is going to stand on the scales, and we can see that Sofia's mass is 30 kilogrammes.

Let's check that you know how to read the scale.

What is the mass of this carrot? Could it be 70 kilogrammes, 70 grammes, or seven grammes? Look carefully, pause the video, and have a think.

Well done for looking so carefully at this scale.

The correct mass for this carrot is 70 grammes.

You can see that's where the black arrow is pointing to.

We know it's not 70 kilogrammes, because the scale says that it measures mass in grammes, and we know it can't be seven, because it's pointing to the number 70, so it must be 70 grammes.

Well done if that's what you said.

Now it's time for you to practise thinking about how you can measure mass in grammes and kilogrammes.

First, you need to choose the most sensible measurement for each mass; for example, the first one says, "My lunchbox has a mass of." Hmm, would it be 90 kilogrammes or 90 grammes? You tick the one that you think is the most sensible.

Next, you're going to have a look at these parcels on these scales and see if you can write the mass of each parcel.

There are six different scales for you to have a look at.

Make sure that you check carefully whether you need to write your mass in grammes or kilogrammes.

Finally, you're going to have a look at these parcels on these scales.

This time, the mass is written on the parcel, and you need to draw an arrow on the scale to show each mass.

Again, there are six different parcels for you to have a go at.

Going to pause the video and have a go at those now.

Off you go.

Well done everyone.

Let's see how you've got on.

My lunchbox has a mass of 90 grammes.

A pencil sharpener has a mass of eight grammes.

My seven-year-old sister has a mass of 26 kilogrammes.

My chair has a mass of three kilogrammes.

Well done if you chose the most sensible measurement for each mass.

Good job.

Now let's have a look at these parcels.

The mass of the first parcel is five kilogrammes.

B is 25 grammes.

C is 50 grammes.

D is 12 kilogrammes.

E is 18 kilogrammes, and F is 85 kilogrammes.

Finally, you needed to draw an arrow to show the mass of each parcel on each scale.

One kilogramme should be here.

14 kilogrammes, this is where you need to draw your arrow, and 45 grammes, you need to draw your arrow here.

Here are the last three for you to have a look at.

Well done if you've drawn your arrows in the correct place each time.

That means that you've really understood how to show mass on different types of scales.

Good job.

Now that you're at the end of the lesson, you have learnt that mass is what we are measuring when we find out how heavy something is.

Kilogrammes and grammes are some standard units of measure that we can use to measure mass.

These objects, a rabbit, an adult's pair of trainers, and a laptop, have a mass that is about one kilogramme, and a 10-pound note, a paperclip, and a raisin are some of the objects that have a mass of about one gramme.

When you want to measure mass, you need to read the scale carefully.

You have thought so carefully about how we can measure mass today.

Well done.

You've done some really hard work.

I hope that I'm going to see you again soon for some more maths learning.

Bye, everyone.