Lesson

Estimating the length of objects can help us in this lesson. Let's try a problem to review.

Choose the best estimate for the length of a fingernail.

A

100 millimetres

B

60 millimetres

C

10 millimetres

D

1 millimetre

Worked Solution

Idea summary

To estimate the length of an object, we can compare it to an object where we have an idea already of its estimated length.

Let's look at the units for volume of \text{mm}^3, \text{cm}^3, and \text{m}^3.

Which of these is the bigger volume?

A

1 \text{ mm}^3

B

1 \text{ cm}^3

Worked Solution

Idea summary

Here are some units of volume from lightest to heaviest: \text{mm}^3, \text{cm}^3, and \text{m}^3.

How do you know which unit to use?

What is the most appropriate unit for measuring the volume of a box?

A

\text{ cm}^3

B

\text{ mm}^3

Worked Solution

Idea summary

A cubic millimetre \left(\text{mm}^3\right) is about as big as a grain of sand.

A cubic centimetre \left(\text{cm}^3\right) is about as big as the end of your thumb.

A cubic metre \left(\text{m}^3\right) is about as big as a washing machine.

Let's look at how we can estimate volume.

The bookshelf shown below has a total volume of 20\,000 \text{ cm}^3.

Select the best estimate for the volume of the books.

A

5000 \text{ cm}^3

B

10\,000 \text{ cm}^3

C

20\,000 \text{ cm}^3

Worked Solution

Idea summary

To estimate the volume of an object, we can compare it to a volume that we already know.

Connect decimal representations to the metric system