Measuring games with centimetres and millimetres
Measure the green strip against a ruler. Read centimetres from zero, find a length when the strip starts elsewhere, read millimetre subdivisions, or move an endpoint to make a requested length. Each of the four routes has twelve tasks, including horizontal and vertical examples. There is no countdown or score penalty for trying again.
Read the distance, not just the endpoint
If a strip starts at 2 cm and ends at 7 cm, it is 5 cm long: 7 − 2 = 5. Count the spaces between the ends, rather than the number of ruler marks. The numbered marks on this ruler are centimetres. In the millimetre route, each smallest interval is 1 mm and ten of them make 1 cm.
Choose a measuring activity
- Read centimetres: whole-centimetre strips starting at zero.
- Start away from zero: subtract the starting mark from the ending mark.
- Read millimetres: count small intervals and relate them to the centimetre labels.
- Make the length: adjust the strip’s end while its start stays fixed.
The ruler explorer lets you change either endpoint, units and direction freely. It displays end minus start and does not award a score or sticker.
Controls and optional working
Type a whole-number length and choose Check length. In the building route, tap the ruler, use the length slider or choose Shorter and Longer. The slider also works with keyboard arrows. Zoom to strip enlarges short millimetre lengths while keeping their endpoints and units unchanged. Tab reaches the answer and action controls; Enter checks an answer. Holding Enter or Space does not skip tasks. Choose Next measurement explicitly after a correct answer.
Show working highlights the measured interval and explains its endpoints. You can use this support at any point. A wrong answer keeps the same task and your existing progress. Vertical rulers run from top to bottom here, with zero at the top. These are selected length activities, not a complete measurement curriculum.
Save a route and return to it
Your draft answer, adjusted endpoint and checked task save separately for each route in this browser on this device. The menu shows where to continue. Restart this route asks before replacing its progress; other routes and earned stickers stay. Working-level changes do not erase a route. The explorer keeps its own settings.
Completing all twelve tasks in a route awards its matching sticker in the shared sticker book. The saved-sticker message appears only when that sticker can be read back. Route-save and sticker-save feedback are checked separately. If saving fails, you can keep playing, but leaving or refreshing may lose the current session. Another browser, device or cleared storage starts fresh; there is no cloud-save claim.
Can I use this ruler to measure a real object?
No. It is a scale drawing for practice, and its physical size changes with the screen. Use a real ruler for objects on your desk. You can then discuss the same ideas of zero, endpoints, equal intervals and units.
Is the game free?
Yes. Play in your browser without signup, downloads or in-game purchases.
For placing numbers on equal intervals, try Number Line Workshop. For comparing distances to nearby multiples, try Rounding Workshop. Browse length and measuring activities or all maths games.