Plan and conduct reproducible investigations

The core idea is that a good investigation is not just “doing an experiment”. The method must match the hypothesis, define what changes and what is measured, state important assumptions, be clear enough to reproduce, and be planned so risks, ethical issues and responsibilities on Country/Place are addressed before work begins.

Planning flow: Question/hypothesis → method match → variables → assumptions → reproducible steps → risk/ethics → Country/Place responsibilities where relevant → conduct and record → review.

E1 — Does the method test the hypothesis?

Compare the proposed method with the hypothesis. If the hypothesis says sunlight affects plant growth, the method should vary sunlight, measure growth and keep other relevant factors such as water and soil as constant as practical. A detailed method can still be invalid if it tests the wrong relationship.

E2 — Variables and assumptions

• Independent variable: deliberately changed.
• Dependent variable: measured outcome.
• Controlled variables: relevant factors kept as constant as practical.
• Assumptions: conditions treated as true or constant, such as instrument calibration, ambient temperature or material purity.

E3 — Reproducibility

A reproducible method states equipment, quantities, sequence, measurements, controls and repeats clearly enough for another investigator to follow. Similar results are expected; exact identical numbers are not required. Reviewing another student’s method can reveal missing steps, vague measurements or uncontrolled variables.

E4 — Assumptions about constants

Examples include assuming room temperature remains stable, materials have comparable properties, substances have expected purity, or measuring devices are accurate. Good investigators identify these assumptions and reduce weak ones by measuring or standardising conditions where practical.

E5 — Risk management

Identify the hazard, possible harm and a specific control. “Be careful” is not enough. For example: hot glassware → burns → use suitable tongs/gloves and allow cooling; chemical splash → eye injury → wear goggles.

E6 — Ethics and living things

Methods involving living organisms should minimise unnecessary harm, stress or injury, use alternatives where appropriate, and follow relevant school or jurisdiction guidance.

E7 — Heritage laws

Field investigations must recognise that First Nations heritage places and objects are protected under state and territory laws. Legal requirements vary by jurisdiction and do not replace local cultural protocols.

E8 — Collaboration with First Nations communities

Ecosystem investigations should be planned with relevant First Nations communities or organisations where appropriate, with agreed protocols, respectful use of knowledge and mutually beneficial outcomes.

E9 — Artefacts and heritage sites

Students should recognise that possible human stonework, artefact scatters and other heritage material must not be harmed or disturbed. Identification should be cautious and context-based; unusual rocks should not automatically be labelled artefacts.

• E1: compare method with hypothesis.
• E2: identify variables and assumptions.
• E3: construct and review reproducible methods.
• E4: recognise assumptions about constant conditions/materials.
• E5: identify and manage risks.
• E6: consider ethics involving living things.
• E7: recognise state/territory heritage laws.
• E8: collaborate with First Nations communities/organisations for mutually beneficial ecosystem investigations.
• E9: recognise and do not harm/disturb artefacts and heritage sites.

1. What makes an investigation reproducible?
   A clear method with specified equipment, quantities, sequence, measurements, controls and repeats that another investigator can follow to obtain reasonably consistent findings.
2. Why must the method match the hypothesis?
   Because the method must actually test the proposed relationship; otherwise the investigation may be reproducible but invalid.
3. What are IV, DV and controlled variables?
   IV = changed factor; DV = measured outcome; controlled variables = relevant factors kept as constant as practical.
4. Why identify assumptions?
   Because an incorrect assumption, such as an uncalibrated thermometer, can affect data and conclusions.
5. What is an example of an assumption?
   Assuming an instrument is accurate, ambient temperature remains stable, or materials have comparable properties.
6. Why manage risks?
   To reduce the chance and severity of harm to students, others, organisms, equipment and the environment.
7. What is one ethical consideration with living things?
   Minimise unnecessary harm or stress and redesign the method if the scientific question can be answered less harmfully.
8. What should happen if a possible heritage artefact is found?
   Leave it undisturbed and follow relevant local protocols, school procedures and legal reporting requirements.
9. Why collaborate with First Nations communities in ecosystem research?
   To support culturally appropriate design, agreed use of knowledge and mutually beneficial outcomes.
10. What is the difference between validity and reproducibility?
    Validity asks whether the design tests the intended question; reproducibility asks whether the method can be repeated consistently.

Exam checklist

• Method directly tests hypothesis.
• IV, DV and controls clearly identified.
• Important assumptions stated and evaluated.
• Measurements, quantities and repeats are specific.
• Hazards linked to specific controls.
• Ethics considered before work with living things.
• Country/Place work follows relevant laws and local cultural protocols.
• Possible artefacts and heritage sites are not disturbed.
• Collaboration is respectful and mutually beneficial.

Common mistakes

• Calling a method valid just because it is detailed.
• Thinking reproducibility means exactly identical results.
• Treating assumptions as facts that do not need checking.
• Writing “be careful” instead of a specific risk control.
• Assuming heritage laws and cultural protocols are the same everywhere in Australia.
• Moving a possible artefact to inspect it.

Useful sentence: “This method is suitable because it changes the independent variable, measures the dependent variable, controls relevant factors and states assumptions, risks and ethical or cultural responsibilities.”

Homework • Practice • Test

• AC9S7I01 — Questions, predictions and hypotheses
• AC9S7I03 — Equipment and data collection