Understand the idea.
Use the labels that are present
An unnumbered tick still has a value. Find two labels and subtract to find the change between them. Divide that change by the number of equal gaps. A scale beginning at 20 does not begin at zero.
From 20 to 60 mL there is a change of 40 mL over eight gaps. Each gap is . Count on from any known label using the same 5 mL jump.
Estimate between ticks
When the pointer lands on a tick, use the tick value. When it lands between ticks, first find the values on either side. A position halfway between 20 and 30 is about 25, and must lie between 20 and 30.
Use about when you are estimating a position the scale does not mark precisely. Do not add extra decimal places that the instrument cannot justify. Check that your reading stays between its neighbouring tick values.
See the method in action.
Fill the silent part of a scale
Read the pointer on the partially numbered millilitre scale.
Worked solution
- 1
Find the change between the end labels.
Only the difference is divided across the eight gaps, not the full value 60.
- 2
Calculate one gap.
The marked spaces are equal, so each represents the same increase.
- 3
Count on from the 40 label.
The pointer is one gap after 40 millilitres.
45 mL.
Find a temperature with few labels
The thermometer scale labels only 0, 10 and 20. Read the pointer.
Worked solution
- 1
Find the value of one temperature gap.
Five equal gaps separate the labelled 0 and 10 marks.
- 2
Count the gaps past 10.
The pointer is two gaps after 10, giving a 4-degree increase.
- 3
Add the increase to the known reading.
The reading is 14 degrees Celsius, between the labelled 10 and 20 marks.
14 °C.
Try it yourself.
Check your understanding
There are four equal gaps between 20 and 40 mL. What is the first tick after 20?
Show answer & reasoning
25 mL
The change is . Four equal gaps mean per gap, so the first tick after 20 is .
Keep practising
6 worksheet questions · 11 marks
Read the questions online
- Read the pointer on the millilitre scale.2 marks
- Read the temperature pointer.2 marks
- A scale labels 30 and 50 with four equal gaps between them. Give the three missing tick labels.2 marks
- A pointer is halfway between 60 mL and 80 mL. Estimate its reading.1 mark
- A pointer is between the 10 cm and 11 cm marks, close to 11. Is 10.8 cm or 11.8 cm a sensible estimate?2 marks
- The labels show 100 and 200 grams separated by five equal gaps. The pointer is two gaps after 100. Find the reading.2 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Read the pointer on the millilitre scale.2 marks
Each gap is 5 mL.
The pointer is three gaps after 20: mL.
35 mL - Read the temperature pointer.2 marks
Each gap is 2 °C.
The pointer is four gaps after 10: °C.
18 °C - A scale labels 30 and 50 with four equal gaps between them. Give the three missing tick labels.2 marks
; .
Count on by 5.
35, 40, 45 - A pointer is halfway between 60 mL and 80 mL. Estimate its reading.1 mark
The halfway amount between 60 and 80 is 70.
About 70 mL. - A pointer is between the 10 cm and 11 cm marks, close to 11. Is 10.8 cm or 11.8 cm a sensible estimate?2 marks
The reading must be between 10 and 11.
11.8 is outside that interval.
10.8 cm. - The labels show 100 and 200 grams separated by five equal gaps. The pointer is two gaps after 100. Find the reading.2 marks
g per gap.
.
140 g
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 ↗