 # 8.07 Order and compare mass

Lesson

## Ideas

We need to remember how to  order numbers  to help us in this lesson. Let's try this problem to practice.

### 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:

33 and 37 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

Summary of the idea

## 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'll use the mass to compare objects, as well as balance scales.

### Examples

#### Example 2

We want to order these animals from heaviest to lightest.

a

Which of these animals is the heaviest?

A
Sparrow
B
Cockatoo
C
Pigeon
Worked Solution
Create a strategy

Plot the weights of the animals on the number line. The heaviest bird's weight will be the furthest to the right on the number line.

Apply the idea

The three weights are plotted on a number line below.

The number line shows that the cockatoo is the heaviest among the three since its weight it the furthest to the right. So the correct answer is Option B.

b

Which of these animals is the second heaviest?

A
Sparrow
B
Cockatoo
C
Pigeon
Worked Solution
Create a strategy

The second heaviest bird's weight will be the middle one on the number line.

Apply the idea

Based on part (a), the number line shows that the pigeon is the second heaviest animal since its weight is in the middle. 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 bird's weight will be the furthest to the left on the number line.

Apply the idea

Based on part (a), the number line shows that the sparrow is the lightest among the three since its weight is furthest to the left. 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