The idea, step by step
Count gaps, not marks
A scale is divided into equal gaps. Look at two labelled marks and count the gaps between them. If the values rise from 0 to 1000 grams in five gaps, each gap represents 1000 ÷ 5 = 200 grams.
There are six boundary marks around five gaps. Counting marks instead of gaps gives the wrong value. Check by stepping through: 0, 200, 400, 600, 800, 1000.
Read from a known label
Once the interval is known, count from a labelled value to the pointer. The pointer above is three gaps after 0. Three groups of 200 grams give 600 grams.
Read the unit on the scale as well as the number. If reading a real instrument, look straight at the mark or liquid level. This reduces mistakes caused by viewing from above, below or the side.
A common trap
There are six tick marks from 0 to 1000, so I divided 1000 by 6.
Instead: Count the five spaces between the six marks. Each space is 200 g.
See the thinking
Read a mass scale
Read the pointer on this mass scale.
- 0 to 1000 spans five gaps, so each gap is 200 g.
- The pointer is three gaps from 0.
- 3 × 200 = 600 g.
Read an unnumbered tick
Read the pointer on the millilitre scale.
- 0 to 100 spans two gaps, so each gap is 50 mL.
- The pointer is one gap after 300.
- 300 + 50 = 350 mL.
Check your understanding
A scale has four equal gaps from 0 to 80 mL. What is one gap worth?
Show answer
20 mL
80 ÷ 4 = 20 mL per gap.
Your turn
6 questions · 11 marks · Work at your own pace.
Read the questions online
- A ruler has 10 equal gaps from 0 to 10 cm. What does each gap represent?1 mark
- Read the mass pointer.2 marks
- Read the liquid pointer.2 marks
- A scale has five equal gaps from 0 to 50 kg. A pointer is four gaps from 0. Find the mass.2 marks
- A temperature scale rises from 10 °C to 30 °C in four equal gaps. Give the values at all five marks.2 marks
- A learner counts the two marks labelled 0 and 10 as two intervals. Explain why that is wrong.2 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- A ruler has 10 equal gaps from 0 to 10 cm. What does each gap represent?1 mark
10 ÷ 10 = 1 cm.
1 cm - Read the mass pointer.2 marks
Five gaps cover 1000 g, so each is 200 g.
The pointer is four gaps from 0: 4 × 200 = 800 g.
800 g - Read the liquid pointer.2 marks
Each small gap is 50 mL.
One gap after 400 is 450 mL.
450 mL - A scale has five equal gaps from 0 to 50 kg. A pointer is four gaps from 0. Find the mass.2 marks
50 ÷ 5 = 10 kg each.
4 × 10 = 40 kg.
40 kg - A temperature scale rises from 10 °C to 30 °C in four equal gaps. Give the values at all five marks.2 marks
The difference is 20 °C.
20 ÷ 4 = 5 °C per gap.
10, 15, 20, 25, 30 °C - A learner counts the two marks labelled 0 and 10 as two intervals. Explain why that is wrong.2 marks
Intervals are spaces between marks, not the marks themselves.
There is one gap between those two marks.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics 2026
Length/mass/capacity/temperature; scaled instruments; partial/unmarked intervals; suitable units and accuracy.
Official curriculum source ↗