When we think about how heavy something is, we are thinking about its mass. We use units of measurement to describe the mass of objects, such as grams and kilograms.

If we are comparing objects that use the same units of mass, such as kilograms, we can compare the numbers. If we have a dog that weighs $40$40 kilograms, and a cat that weighs $19$19 kilograms, we can compare $40$40 to $19$19. Since $40$40 is a larger number than $19$19, we can say that the dog is heavier than the cat, or that the cat is lighter than the dog.

Let's work through some examples in this video.

Careful!

When comparing mass, remember to check that you are comparing things using the same unit of measurement.

Worked examples

question 1

We want to compare the masses of these animals.


Cat	Mouse	Dog

Which of these animals is the $heaviest$ ?
$Mouse$
A
Cat
B
$Dog$
C
Which of these animals is the $lightest$ ?
$Mouse$
A
$Dog$
B
Cat
C
Which animal is closest in mass to $10$10kg?
$Cat$
A
$Mouse$
B
$Dog$
C

Question 2

A $moth$ has a mass of $3$3 grams, a $butterfly$ has a mass of $6$6 grams.

Which insect is heavier?
The $butterfly$ .
A
The $moth$ .
B

Question 3

A local primary school had a cupcake sale and the masses of each cupcake are shown:

Cupcake	Mass (grams)
$Banana$	$91$91
$Blueberry$	$68$68
$Mud-cake$	$89$89
$Choc-chip$	$77$77

Which cupcake was closest to $100$100 grams?
$Mud-cake$
A
$Banana$
B
$Choc-chip$
C
$Blueberry$
D
Which cupcake is the lightest?
$Blueberry$
A
$Mud-cake$
B
$Banana$
C
$Choc-chip$
D
Which are the two heaviest?
$Banana$
A
$Blueberry$
B
$Mud-cake$
C
$Choc-chip$
D

Compare objects by mass

Comparing mass

Worked examples

question 1

Question 2

Question 3

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