Year 9 Science · AC9S9I03

Equipment, precision and replicable data

Choose equipment whose range and resolution suit the question, record measurements honestly, collect a useful sample and use digital tools because they improve…

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Key conceptTeach from the board

Instrument choice must fit the expected values. A 1 m ruler cannot sensibly resolve 0.1 mm; a 10 mL measuring cylinder may be more suitable than a beaker for small volumes. Record only digits justified by the scale or sensor resolution.

A larger useful sample can reduce the influence of random variation and better represent a population. Repeats help estimate consistency. Digital sensors can collect many measurements rapidly, but they still require calibration, sensible sampling rates and correct units.

Worked examplesWe do

Worked examples

AC9S9I03 - Equipment, precision and replicable data
Example 1

Choose between a beaker, measuring cylinder and pipette for a 5.0 mL measurement.

Example 2

Round a reading to precision supported by a given scale.

Example 3

Explain why five repeated timings are more informative than one.

Example 4

Select a useful digital sampling rate for a changing temperature graph and justify.

Curriculum examplesCopied content

Australian Curriculum v9.0 — AC9S9I03: equipment selection, precise data, useful samples and replicable collection.

Victoria Levels 9–10 — VC2S10I03:Exact.

NSW Stage 5 — SC5-WS-01, WS-04, WS-05:Exact/Partial accurate observation, conducting investigations and processing/representing data together cover the intent.

LessonAC v9VictoriaNSW
Equipment/measurementDirectDirectWS-01/04
Recording/data toolsDirectDirectWS-05
Questions and answersWith answers
  1. What is resolution? The smallest change an instrument can meaningfully distinguish.
  2. Why repeat measurements? To reveal random variation and estimate a more stable result.
  3. Why use a useful sample size? To reduce over-reliance on unusual individual observations and better represent the target population.
  4. When are digital tools useful? When they improve appropriate collection, precision, frequency or recording—not merely because they are digital.
Practice and reviewReady for practice
  • More decimal places mean better data. Extra digits can be false precision.
  • A digital instrument is automatically accurate. Calibration and sensor limitations still matter.
  • One precise reading is enough. Repeats/sample size address variation.
  • More data are always better. Data must be relevant, well sampled and interpretable.
Curriculum alignmentStart here
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