Maths topic

length, mass and capacity

Length, mass and capacity are different kinds of measurement. First choose the question you are asking, then choose a tool and unit that fits.

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the big idea

Different measurements answer different questions. Length asks how long or how far. Mass asks how heavy. Capacity asks how much a container can hold.

length how long?
mass how heavy?
capacity how much can it hold?

choose the measurement

Change the measurement type and notice how the question, tool and unit change.

How long? ruler for pencil

Length: How long?

questionHow long? toolruler for pencil unitsunits: mm, cm, m, km exampleA pencil might be 14 cm long.
measure

length measures how long

Length measures distance from one point to another.

  • Use length for questions like how long, how tall, how wide or how far.
  • Rulers, tape measures and trundle wheels measure length.
  • Common length units include mm, cm, m and km.
How long? ruler for pencil
0 1 2 3 4 5

mass measures how heavy

Mass tells how heavy something is.

  • Use mass when comparing heavier and lighter objects.
  • Balance scales, kitchen scales and digital scales measure mass.
  • Common mass units include g, kg and t.
How heavy? scale for school bag
featherlighter school bagheavier

capacity measures how much a container holds

Capacity tells how much liquid or material a container can hold.

  • Use capacity for containers such as bottles, cups, jugs and buckets.
  • Measuring jugs and marked containers measure capacity.
  • Common capacity units include mL and L.
How much can it hold? measuring jug for water bottle
empty half full full

choose the right measurement

The question tells you which measurement to use.

  • How tall is the door? Choose length.
  • How heavy is the bag? Choose mass.
  • How much water fits in the bottle? Choose capacity.
How long? ruler for pencil
How long? Length
How heavy? scale for school bag
How heavy? Mass
How much can it hold? measuring jug for water bottle
How much can it hold? Capacity

tools and units must match

A measurement is clearer when the tool and unit match the thing being measured.

  • A ruler and centimetres suit a pencil length.
  • A scale and grams or kilograms suit mass.
  • A measuring jug and millilitres or litres suit capacity.
Length ruler for pencil units: mm, cm, m, km
Mass scale for school bag units: g, kg, t
Capacity measuring jug for water bottle units: mL, L

measurement words

These words help choose the right kind of measurement.

1 length how long?

distance from one point to another

2 mass how heavy?

how heavy an object is

3 capacity how much?

how much a container can hold

4 unit label

the label that tells the size being measured

5 tool measurer

the item used to measure carefully

measurement facts

fact Length asks how long or how far
fact Mass asks how heavy
fact Capacity asks how much a container holds
fact Rulers measure length
fact Scales measure mass
fact Measuring jugs measure capacity

real world examples

height measuring how tall a student is
distance measuring how far it is across the oval
cooking measuring the mass of flour on a scale
shopping comparing the mass of fruit bags
drink bottles checking how much water a bottle holds
science choosing a tool before measuring

quick measurement quiz

Try a few ideas. This quiz only asks about ideas shown on this page.

Which measurement tells how long something is?

Which measurement tells how heavy something is?

Which measurement tells how much a container can hold?

Which tool would suit measuring the length of a pencil?

Which unit would suit the capacity of a water bottle?