The idea, step by step
Three kinds of measurement
Length tells how far or how long. Use centimetres (cm) for a pencil and metres (m) for a room.
Mass tells how heavy an object is. A small packet might be measured in grams (g), while a person is measured in kilograms (kg).
Choose a unit that fits
Capacity tells how much a container can hold. Use millilitres (mL) for a small drink and litres (L) for a large bottle.
Keep the unit with its number. A label of 2 L does not mean the same capacity as 2 mL.
| What to measure | Useful tool | Possible unit |
|---|---|---|
| Ribbon length | Ruler | cm |
| Mass of fruit | Scales | g |
| Water in a jug | Measuring jug | mL |
A common trap
Choosing the same unit for everything.
Instead: Match the unit to both the attribute and the size.
See the thinking
A classroom
Choose centimetres or metres for a classroom length.
- A classroom is much longer than a pencil.
- Metres give a convenient number, such as 8 m.
A small juice carton
Which label fits one small juice carton: 200 mL or 200 L?
- One carton holds a small drink.
- 200 L would fill many large containers.
Check your understanding
Which unit fits the mass of an apple: g, m or L?
Show answer
g
Grams measure a small mass; metres measure length and litres measure capacity.
Your turn
6 questions · Work at your own pace.
Read the questions online
- Choose cm or m for a pencil length.
- Choose g or kg for the mass of a child.
- Choose mL or L for the capacity label on a typical household bucket: 9 ___.
- What does a kitchen scale measure: length, mass or capacity?
- What does L stand for on a bottle?
- A desk is labelled 120 kg long. Correct the unit and explain.
Read the worked solutions
- Choose cm or m for a pencil length.
A pencil is a short object.
cm - Choose g or kg for the mass of a child.
A child has a mass of many kilograms.
kg - Choose mL or L for the capacity label on a typical household bucket: 9 ___.
9 mL is tiny; a bucket can hold several litres.
L - What does a kitchen scale measure: length, mass or capacity?
Scales measure how heavy something is.
Mass - What does L stand for on a bottle?
L is a capacity unit.
Litre - A desk is labelled 120 kg long. Correct the unit and explain.
Length needs a length unit.
120 cm is a sensible desk length.
120 cm is sensible; kg measures mass.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum
Length/mass/capacity units; estimation; reading labelled measuring instruments.
Official curriculum source ↗