Measure length with uniform informal units
A clear starting point, worked steps and space to practise.
Start here
You can measure length by placing equal units end to end.
Always name the unit. Seven blocks and seven paperclips need not be the same length.
1 Work through these steps
- Choose units that are all the same length.
- Start at one end of the object.
- Place the units with no gaps or overlaps.
- Count them and name the unit.
2 Follow a worked example
A book is exactly 7 equal blocks long. A pencil is 5 of the same blocks long. How much longer is the book?
Reduce diagram
Scroll across the diagram if needed. Keyboard users can focus the diagram and use the arrow keys.
- Both lengths use the same block unit.
- 7 − 5 = 2.
- The book is 2 blocks longer.
3 Try it yourself
Show each step on paper or open Working out. Then check the answer.
-
A strip is 6 equal cubes long. You add a piece 3 cubes long. How long is it now?
Check answer 1
Answer: 9 cubes long
6 + 3 = 9, using the same cube unit.
Scratchpad · Not saved
Working out
Draw with a finger, pen or mouse, or type your working below.
Your working stays on this page. It is not submitted or saved, and clears when you leave or reload.
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
- You can measure length by placing equal units end to end.
- Always name the unit. Seven blocks and seven paperclips need not be the same length.
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.