# 10.08 Order and compare mass

Lesson

## Ideas

We need to remember how to  order numbers  to help us in this lesson.

### Examples

#### Example 1

Order these numbers from largest to smallest.

a

73, \, 33, \, 37

Worked Solution
Create a strategy

We should order the tens first, then the ones.

Apply the idea

The numbers in the place value table are shown:

37 and 33 have the same smallest tens digit, so they are smaller than 73.

But 33 has the smaller ones digit, so 33 is smaller than 37.

The numbers from largest to smallest are: 73,\,37,\, 33

b

671, \, 167, \, 617

Worked Solution
Create a strategy

We should order the hundreds first, then the tens, then the ones.

Apply the idea

The numbers in the place value table are shown:

167 has the smallest hundreds digit so it is the smallest number.

671 and 617 have equal hundreds digits, but 617 has the smaller tens digit.

The numbers from largest to smallest are: 671,\,617,\, 167

Idea summary

When we use place value to order numbers, always start with the highest place value.

## Order objects by mass

We could weigh each object in a group to put them in order but we could also use balance scales. We can work out which object is heavier or lighter out of two objects, then compare it to another object.

In the video, we will use the mass to compare objects, as well as balance scales.

### Examples

#### Example 2

We want to order these animals from lightest to heaviest.

a

Which of these animals is the heaviest?

A
Sparrow
B
Cockatoo
C
Pigeon
Worked Solution
Create a strategy

The heaviest animal will be the one with the largest number on the scales. Plot the weights of the animals on a number line.

Apply the idea

The three weights are plotted on a number line below.

Based on the number line, the number line shows that the cockatoo is the heaviest among the three. So the correct answer is option B.

b

Which of these animals is the second lightest?

A
Sparrow
B
Cockatoo
C
Pigeon
Worked Solution
Create a strategy

The second lightest animal will be the one with the second smallest number on the scales.

Apply the idea

Based on part (a), the number line shows that the pigeon is the second lightest animal. So the correct answer is option C.

c

Which of these animals is the lightest?

A
Sparrow
B
Pigeon
C
Cockatoo
Worked Solution
Create a strategy

The lightest animal will be the one with the smallest number on the scales.

Apply the idea

Based on part (a), the sparrow is the lightest among the three. So the correct answer is option A.

Idea summary

To put objects in order by mass, we need to make sure we are using the same unit of measurement, such as grams, for each object we are comparing.

### Outcomes

#### MA2-12MG

measures, records, compares and estimates the masses of objects using kilograms and grams