ACARA v9 CONTENT DESCRIPTION “plan and conduct reproducible investigations to answer questions and test hypotheses, including identifying variables and assumptions and, as appropriate, recognising and managing risks, considering ethical issues and recognising key considerations regarding heritage sites and artefacts on Country/Place”
Builds on the fair test. A reproducible field investigation goes further: you not only change one variable and control the rest, you also name your assumptions, manage real risks in the field, and plan to act ethically on Country and Place so that another group could safely and respectfully repeat exactly what you did.
The field question and the variables
Imagine a class investigating a creek that runs through bushland. The question is whether pebbles get smaller the further you travel downstream. The variable you change is the distance downstream where you sample. The thing you measure is the average pebble width. Everything else, the same sieve, the same number of pebbles per site, the same person reading the ruler, is held constant. Naming these turns a wander along the creek into a plan someone else could follow.
Assumptions you are making
Every plan rests on assumptions, and a good scientist states them rather than hiding them. Here you assume the rock type stays roughly the same along the creek, that the day’s weather has not just washed in fresh gravel, and that your sample of pebbles at each site represents the whole site. If an assumption turns out to be false, it could explain a result without distance being the cause at all.
Set up the stream investigation as a fair test
You are testing whether pebble size changes with distance downstream. Distance is the one thing you change. Decide what to do with every other variable so the test stays fair.
Your class samples pebbles at five points along a bushland creek, from near the source down to the lower bank. You want to know whether pebbles get smaller further downstream.
Variable being tested: Distance downstream from the source (five sampling sites) (this one we change)
The sieve and ruler used to sort and measure pebbles
The number of pebbles measured at each site (say, twenty)
The person reading the measurement and how width is defined
The time of day and that sampling happens on one dry day
Not a fair test yet: more than one thing is changing, so you could not tell which change caused the result. Hold every other variable the same.
Managing the risks in the field
A school creek is a real place with real hazards, so risk management is part of the plan, not an afterthought. Slippery banks, deep or fast-moving water, sharp rocks, sun and heat all need a response. You decide to work in pairs, stay on stable ground away from deep water, wear hats and sunscreen, handle rocks with gloves, and wash hands before eating. A method that cannot be carried out safely cannot be repeated safely either.
One method choice that shapes reproducibility
How you fix the risk often changes how repeatable the method is. Choosing exactly where to sample is one such choice. A plan that says only follow the creek and grab some pebbles is quick but vague, and the next group would sample different spots. Marking five fixed distances with a tape measure takes longer but means anyone can return to the same sites. The trade-off between speed and repeatability is worth weighing openly.
Choose how to fix the sampling sites
Each way of deciding where to sample carries a benefit and a cost for how safe and reproducible the investigation is. Pick one to see the trade-off.
Your group must decide how to set the five sampling sites along the creek. The choice affects both safety and whether another class could repeat your method.
Choose a response to see what is gained and what is given up.
Heritage sites and artefacts on Country and Place
Planning a field investigation also means recognising that the land you work on is Country and Place. Some sites, rocks and artefacts hold cultural heritage significance for Aboriginal and Torres Strait Islander peoples. Arrangements of stones, marked or worn rocks, scarred trees and grinding grooves can be culturally and legally protected. The right plan is to leave any such site, rock or artefact undisturbed, never remove or damage it, and seek permission and guidance from Traditional Owners before working in an area. This is a genuine part of good investigation design, not an optional extra.
Sorting the plan: reproducible, safe, ethical and respectful
Before going to the creek, check each planned action against the claim that this is a well-designed investigation: one that is reproducible, safe, and respectful of heritage on Country and Place. Sort each action by whether it genuinely supports that claim or whether it does not belong in the plan at all.
Judge the plan for the creek investigation
The claim: this plan is reproducible, safe, ethical and respectful of heritage. Decide which actions support it.
Claim: This plan is a reproducible, safe and heritage-respecting field investigation of pebble size along the creek.
Mark five fixed distances with a tape measure and record them so others can return to the same sites.
If a marked or worn rock or stone arrangement is found, leave it undisturbed and seek guidance from Traditional Owners before going further.
Work in pairs, wear hats and sunscreen, and stay clear of deep or fast-moving water.
Collect an interesting carved rock from the bank to bring back and display in the classroom.
Let each pair measure pebbles in whatever way feels quickest, without a shared rule.
Decide whether each statement is evidence for the claim, or not.
Why this matters
A reproducible investigation is one another person can trust because they could repeat it. For field science that means more than controlling variables: it means stating your assumptions, managing real risks, and acting ethically and respectfully on Country and Place. Geologists, ecologists and heritage officers plan exactly this way, so that the evidence is reliable and the land and its cultural heritage are protected.
Quick self-check
1. You want to test how distance downstream affects the size of pebbles in a creek. Which is the variable you change?
2. An assumption built into this stream investigation might be that...
3. A reproducible field method is one where...
4. Which is a sensible risk-management step for a creek-bank investigation?
5. You notice an arrangement of stones and old grinding marks on a rock by the creek. The right action is to...