Resolution describes the smallest scale difference an instrument can distinguish. A millimetre scale provides finer divisions than a centimetre scale, but alignment and calibration still matter. Read an object’s two endpoint positions and subtract them. Reporting extra digits without supporting scale information does not create a more trustworthy measurement.
Engineering and scientific investigation · Discover & try
How much can a ruler reading tell you?
Reading level 3 of 5 · IndependentChange
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Resolution
The smallest change distinguishable on a scale.
Endpoint difference
End reading minus start reading.
Watch · Try · Explain
See how it works
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An ideal on-screen ruler with illustrative dimensions. Compare scale spacing, endpoint readings and their difference.
What to look for
- Move the object away from zero.
- Compare coarse and fine divisions.
Explain what you noticed
A new object’s start reads 20 mm and its end reads 63 mm. What is its length?
Keep this idea: Use the endpoint difference and respect what the scale can actually resolve.
Follow the sources
- NIST/SEMATECH Engineering Statistics Handbook — Resolution
- NIST — Metric Ruler, Special Publication 376
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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