Australian Curriculum v9 / ACiQ Year 7 Science - Unit 1 - Fair, safe and reproducible investigations

Fair, safe and reproducible investigations

Plan and improve investigations so comparisons are fair, risks are managed and methods can be reproduced.

Updated 2026-07-24 - 8 min read

Plan and improve investigations so comparisons are fair, risks are managed and methods can be reproduced. This note connects the core scientific model to a worked example, an inquiry design and the limits of the evidence.

Core model

Fair asks whether the comparison isolates the intended change. Safe asks whether hazards and harms are managed. Reproducible asks whether another group can follow the method without guessing. Repeated asks whether evidence is consistent.

Accessible diagram description: Four linked boxes are labelled fair, safe, reproducible and repeated. Fair points to controlled variables; safe to hazard–harm–control; reproducible to quantities, units and ordered steps; repeated to spread and consistency.

A model is useful because it highlights relationships that help explain or predict evidence. It is not a perfect copy of reality. Always state what the representation includes, what its arrows or symbols mean, and one relevant limitation.

Authored representation workshop

Fair, safe, reproducible and repeated

Accessibility description: Four connected checks lead to trustworthy evidence: fair controls competing variables; safe links the bouncing-ball hazard to harm and a clear test zone; reproducible specifies heights, units and a no-push release; repeated compares three trials at each height.

Represented parts

  • Fair: same ball, surface and release
  • Safe: clear marked zone and retrieve after stopping
  • Reproducible: exact heights, ruler rule and units
  • Repeated: three trials at every height

Represented relationships

  • Fair: same ball, surface and release -> Safe: clear marked zone and retrieve after stopping (design check)
  • Safe: clear marked zone and retrieve after stopping -> Reproducible: exact heights, ruler rule and units (method check)
  • Reproducible: exact heights, ruler rule and units -> Repeated: three trials at every height (evidence check)

Learner action: Audit the four connected design checks. For each check, name one concrete detail from the representation and explain why repeated trials cannot repair a comparison that was unfair or unsafe.

Ball rebound-height trials

Accessibility description: Mean rebound height rises with drop height. At 80 centimetres, trial 2 is much lower than trials 1 and 3, so the release or reading should be checked.

| Drop height (cm) | Trial 1 rebound (cm) | Trial 2 rebound (cm) | Trial 3 rebound (cm) | | --- | --- | --- | --- | | 40 | 18 | 19 | 18 | | 60 | 29 | 30 | 30 | | 80 | 42 | 19 | 43 | | 100 | 53 | 52 | 54 |

*Same rubber ball, floor, ruler position and no-push release.*

Learner action: Audit and rewrite a vague rebound-height method. Produce an ordered, numbered method with exact drop heights, a no-push release, a measurement rule and three repeats; add a hazard-harm-control chain; then use the supplied trials to flag the anomalous result and propose a targeted check.

The representation and table are supplied evidence. Do not replace a represented value, relationship or anomaly with an expected result. If a visual version is created, preserve this text-equivalent information and define every symbol, arrow, heading and unit.

Worked example

The reasoning routine is:

  1. identify the observation, measurement or represented relationship
  2. select the relevant science idea
  3. connect the idea to the evidence in a complete sentence
  4. qualify the answer when the evidence or model has a boundary

Inquiry connection

Question: How does drop height affect the rebound height of the same rubber ball on the same surface?

Reasoned hypothesis: If drop height increases, rebound height will increase because the ball has more energy before impact.

  • Independent variable: drop height
  • Dependent variable: maximum rebound height
  • Relevant controls: ball, surface and release method
  • Hazard: a bouncing ball can strike a person or cause a trip
  • Risk control: use a clear marked area, keep observers behind the line and retrieve the ball only after it stops
  • Reproducibility detail: state each drop height, the no-push release, ruler position, reading rule and three repeats

Possible data finding: mean rebound height increased at each drop height, while one trial at 80 cm was much lower than the other repeats.

Evidence-based interpretation: The means support the hypothesis, but the low trial should be checked for a poor release or reading error.

Limitation: Only one ball and one surface were used, so the relationship may differ for other materials.

This investigation frame recurs across Year 7 Science. A sound response names a testable relationship, matches the hypothesis to the same variables, manages a realistic risk, specifies quantities and measurement rules, analyses the full data pattern, supports a claim with evidence and states what the evidence cannot establish.

Common errors and corrections

  • Error: Treating fair as meaning all results must match. Correction: Return to the core model and identify the exact evidence or relationship before answering.
  • Error: Assuming repeated trials repair a systematic flaw. Correction: Return to the core model and identify the exact evidence or relationship before answering.
  • Error: Using vague quantities such as 'some' or 'carefully'. Correction: Return to the core model and identify the exact evidence or relationship before answering.
  • Error: Writing generic safety advice that does not address a hazard. Correction: Return to the core model and identify the exact evidence or relationship before answering.

Practice

  1. Find the confounding variable in a towel test.
  2. Write a hazard–harm–control chain for warm water.
  3. Rewrite a vague method step with equipment, quantity and unit.
  4. Explain one limitation that repeats do not remove.

Transfer task

Apply the topic to the investigation below without relying on a teacher or AI to mark the reasoning.

Evidence status: activity only. Use the task-specific rubric below for self-review or teacher feedback; completion does not automatically award mastery.

Context: How does drop height affect the rebound height of the same rubber ball on the same surface?

  1. Rewrite the question if it does not clearly name the relationship and measurable outcome.
  2. Write the matching reasoned hypothesis: include the expected direction and the science idea that justifies it.
  3. Identify the independent variable, dependent variable and at least three relevant controlled variables.
  4. Write a six-step reproducible method. Include equipment, quantities, units, an ordered measurement rule and at least three repeated trials for each condition.
  5. State the hazard, possible harm and a practical control. The control must address the stated hazard rather than being generic advice.
  6. Design a results table with headings and units. State which graph or other representation would best show the relationship and why.
  7. Use this possible finding: mean rebound height increased at each drop height, while one trial at 80 cm was much lower than the other repeats. Describe the overall pattern, identify any anomaly and state a reasonable check.
  8. Write a conclusion using claim, specific evidence and scientific reasoning. Finish with this limitation: Only one ball and one surface were used, so the relationship may differ for other materials.

Correction guide: Compare the question and hypothesis to confirm they use the same two variables. In the method, circle every quantity and unit and underline every controlled condition. In the data response, separate the broad pattern from any anomalous result. In the conclusion, highlight the evidence sentence and box the limitation. If one of these parts is absent, revise that part before checking the scientific vocabulary.

An excellent transfer response is precise without pretending the evidence is perfect. It makes the chain from question to method to data to claim visible, and it explains how the core model applies in the unfamiliar context.

Task-specific inquiry rubric

  • Question and hypothesis for drop height and maximum rebound height: Names the same measurable relationship in both and gives a scientific reason. Revise if needed: Align the changed factor, measured outcome and predicted direction.
  • Fair, safe and reproducible method: Controls ball, surface and release method, manages "a bouncing ball can strike a person or cause a trip", and specifies quantities, units, measurement rules and repeats. Revise if needed: Replace vague directions and generic safety advice with operational detail.
  • Data and analysis plan: Provides labelled headings and units, an appropriate representation, a way to describe the whole pattern and a rule for checking anomalies. Revise if needed: Show how evidence will answer the question before collecting it.
  • Scientific interpretation and boundary: Links the expected evidence to fair, safe and reproducible investigations and anticipates this boundary: Only one ball and one surface were used, so the relationship may differ for other materials. Revise if needed: Explain the science link and state what the design cannot establish.

Self-check

For each response, check:

  • Did I use the correct scientific vocabulary?
  • Did I refer to the specific evidence, feature or data?
  • Did I explain the link rather than only naming it?
  • Did I avoid claiming more than the model or data support?
  • If an investigation is involved, did I address question, hypothesis, variables, safety, reproducibility, data, evidence and limitations?

Sources