Lesson

Can you estimate lengths that use centimetres or metres?

Choose the best estimate for the length of a classroom.

A

4 metres

B

60 metres

C

100 metres

D

10 metres

Worked Solution

Idea summary

When estimating length, 1 \text{ cm} (centimetre) is about as big as your thumbnail, and 1 \text{ m} (metre) is about as long as two normal steps (for an average Year 3 student).

This video has a look at the units of millimetres \text{(mm)}, centimetres \text{(cm)}, metres \text{(m)}, and kilometres \text{(km)} and how to tell which are bigger or smaller.

A bee is 11 \text{ mm} long. A fly is 14 \text{ mm} long. Which insect is longer?

A

Fly

B

Bee

Worked Solution

Idea summary

When estimating length, we can use \text{mm} (millimetres) for very small objects,\text{ cm} (centimetres) for small objects, \text{m} (metres) for big objects, and \text{km} (kilometres) for longer distances.

This video shows you how to use some strategies to tackle problems.

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.

In this video we look at some familiar things, to get an idea of which unit of measurement we need to use.

Choose the most appropriate unit of measure for the height of a tree.

A

Metres

B

Kilometres

C

Centimetres

Worked Solution

Idea summary

1 \text{ mm} is about a thick as your fingernail.

1 \text{ cm} is about as wide as your fingernail.

1 \text{ m} is about the same as two steps.

1 \text{ km} is about the size of a one and a half laps around the school oval.