The idea, step by step
Three different questions
Length tells us how long, high or wide something is. Compare two ribbons by lining up one end.
Mass tells us how heavy something is. A balance can help compare masses. Capacity tells us how much a container can hold.
Choose the question before the tool
For a path, ask how long it is. For a school bag, ask how heavy it is. For a bottle, ask how much it holds.
A tall thin cup can hold less than a short wide cup. To compare capacity, compare the space inside, not only the height.
A common trap
A taller container always holds more.
Instead: Height alone does not tell us capacity. Fill both with the same cup to compare.
See the thinking
A new ribbon
Mia needs ribbon to go around a parcel. Should she think about length, mass or capacity?
- She needs enough ribbon to reach around the parcel.
- This asks how long the ribbon is.
Filling a bottle
A bottle holds 5 equal cups. A jug holds 8 of those cups. Which has the greater capacity?
- The same cup measures both containers.
- 8 is more than 5.
Check your understanding
Which attribute tells how heavy a lunch box is?
Show answer
Mass.
Mass compares how heavy objects are. Length and capacity answer different questions.
Your turn
6 questions · Work at your own pace.
Read the questions online
- Would you measure length, mass or capacity to choose a ribbon long enough for a present?
- Would you compare length, mass or capacity to find the heavier school bag?
- Would you measure length, mass or capacity to find how much water a bucket holds?
- A jar holds 4 equal scoops of rice. A tub holds 7 of the same scoops. Which holds more?
- A toy balances with 6 equal cubes. A block balances with 9 of those cubes. Which has more mass?
- A shoe is 8 equal blocks long. A pencil is 5 of the same blocks long. Which is longer?
Read the worked solutions
- Would you measure length, mass or capacity to choose a ribbon long enough for a present?
We need to know how long the ribbon is.
Length. - Would you compare length, mass or capacity to find the heavier school bag?
Heavier and lighter describe mass.
Mass. - Would you measure length, mass or capacity to find how much water a bucket holds?
Capacity describes what fits inside.
Capacity. - A jar holds 4 equal scoops of rice. A tub holds 7 of the same scoops. Which holds more?
7 scoops is more than 4.
The tub. - A toy balances with 6 equal cubes. A block balances with 9 of those cubes. Which has more mass?
9 equal cubes have more mass than 6.
The block. - A shoe is 8 equal blocks long. A pencil is 5 of the same blocks long. Which is longer?
8 blocks is longer than 5 of the same blocks.
The shoe.
Curriculum reference & lesson scope
Australian Curriculum v9 / SA Curriculum 2026
Length, mass and capacity; uniform informal units; smaller units for accuracy; comparison.
Official curriculum source ↗