Measure length in centimetres and metres
A clear starting point, worked steps and space to practise.
Start here
A ruler measures the distance between two positions, not simply the final number you see.
Starting from zero is convenient, but any two marks work if you subtract the start.
1 Work through these steps
- Check the ruler unit and the size of each gap.
- Read where the object starts.
- Read where it finishes.
- Subtract start from finish.
2 Follow a worked example
A pencil starts at 2 cm and ends at 11 cm. How long is it?
Reduce diagram
Scroll across the diagram if needed. Keyboard users can focus the diagram and use the arrow keys.
- The starting mark is 2 cm.
- The finishing mark is 11 cm.
- 11 − 2 = 9, so the pencil is 9 cm long.
3 Try it yourself
Show each step on paper or open Working out. Then check the answer.
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A strip runs from 3 cm to 8 cm. Find its length.
Check answer 1
Answer: 5 cm
8 − 3 = 5 cm.
Scratchpad · Not saved
Working out
Draw with a finger, pen or mouse, or type your working below.
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Check your understanding
Explain the worked example in your own words. Say why the method works, not just what the answer is.
Skills and explanation links
Key ideas taught here
- A ruler measures the distance between two positions, not simply the final number you see.
- Starting from zero is convenient, but any two marks work if you subtract the start.
Method and checking
For parents and teachers
- Ask your child to explain the method aloud before writing the answer.
- Use a real-life context at home, such as shopping, cooking, sport scores, maps or timetables.
- Praise clear working and checking, not only speed.
- Use counters, blocks, drawings and everyday objects before moving to written symbols.
Practise choosing a method from the information in the question. The examples here are Pi Leo Academy learning activities. Official NAPLAN testing takes place in Years 3, 5, 7 and 9; a topic appearing in these notes does not mean it is tested in NAPLAN.
These notes provide guided examples and practice; they do not certify completion of every curriculum requirement.