Repeated tests for reliability
Distinguish between precision (consistency of repeated readings) and accuracy (closeness to true value), use significant figures and standard form correctly, and choose and use appropriate measuring instruments to minimise uncertainty
Lesson
Set out your lesson
“Precision describes agreement among repeats under stated conditions. Accuracy concerns agreement with a suitable reference. Close repeats can all be biased. Resolution is the smallest readable marked step, not a guarantee of accuracy. Do not add unsupported digits. Safety: Use a light closed book and intact ruler on a stable surface; no medical or chemical measurements. Stop: End after five readings and two practice values. Do not calibrate equipment, weigh substances or add unsupported decimal places.”
Bring to the table
- Millimetre-marked ruler and one closed book
- Paper and pencil
Extra for the adult
Worked example. Answer: A is consistent but high against the illustrative reference; repeats do not remove that bias. B agrees more closely. The practice results are 12.4 cm = 1.24 × 10^1 cm and 0.0048 m = 4.8 × 10^-3 m: each next digit is 6, so round upward.
Optional challenge. Why can averaging biased readings preserve bias?
What to notice. Keep raw readings and calculations. Note ruler divisions, alignment help and no book-length reference.
Share and support
Family records and proof options
Keep a record of your learning
Save photos, notes, and attendance. Export a proof packet for compliance or portfolio reviews.
Learning resources
Extra practice links — they do not replace Gakuva’s teaching approach.
US EPA · Practice link — not the full lesson
Students
Before you open · source notes
Students supports Repeated tests for reliability. An adult previews and guides; this is a learning page, not a scored quiz.
Free educational page, no sign-in required for the tested path.
Before you openAsk the learner one fact they learned and one question they still have.
Opening this link does not save learning or assess mastery.
Source, access and review notes
Public US EPA page. An anonymous GET on 2026-11-12 returned HTTP 200 with no login or payment prompt for this URL. Opening the link does not save practice or assess mastery. An adult should preview and guide the learner.
US EPA. “Students.” External page; Gakuva does not copy, host, embed, or redistribute materials.
Unknown — link only
Check understanding
- Explains the distinction between precision and accuracy with examples
- Rounds measurements to an appropriate number of significant figures
- Selects a measuring instrument with appropriate resolution for the context (e.g. choosing a 10 ml measuring cylinder rather than a 1-litre measuring jug for a 5 ml measurement)
“If your child weighed the same stone five times and got very similar answers but they were all slightly too high, could they explain the difference between being precise and being accurate — and why having lots of repeats doesn’t always fix the problem?”
Curriculum record
- Type
- Conceptual
- Subject
- Science
- Domain
- Scientific Inquiry
- Age range
- Ages 11–12
Standards