ACARA v9 CONTENT DESCRIPTION “plan and conduct repeatable investigations to answer questions including, as appropriate, deciding the variables to be changed, measured and controlled in fair tests; describing potential risks; planning for the safe use of equipment and materials; and identifying required permissions to conduct investigations on Country/Place”
Builds on earlier fair-test planning. Now you plan an investigation that you can repeat: you decide which variable to change, which to measure, and which to keep controlled, you describe the risks, you set the equipment up safely, and you work out what permissions you need before investigating on Country or Place.
The dissolving investigation
You want to find out whether warmer water dissolves sugar faster. You put the same amount of sugar into the same amount of water, stir it the same way, and time how long the sugar takes to disappear. The one thing you change is the water temperature: cold, warm and hot. Everything else, the amount of sugar, the amount of water and the stirring, you keep the same.
Changed, measured, controlled
A repeatable investigation names three kinds of variable. The variable you change is the water temperature. The variable you measure is the time it takes for the sugar to fully dissolve. The variables you control are kept the same every run: the amount of sugar, the amount of water, and how you stir. When only the temperature changes, any difference in the dissolving time must be due to the temperature.
Plan the dissolving test: change the temperature, control the rest
You are testing whether warmer water dissolves sugar faster. Choose the one variable you change, and keep every other variable controlled.
One spoon of sugar, the same amount of water each time, and three water temperatures to try: cold, warm and hot. You want to find out how temperature alone changes the dissolving time, so every other variable must be kept the same.
Variable being tested: The temperature of the water (cold, warm or hot) (this one we change)
The amount of sugar you add (use the same amount every run)
The amount of water in the cup (use the same amount every run)
How you stir the water (stir the same way every run)
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.
Repeating trials and naming the risks
One run can give an odd result. Repeating each temperature three times and taking the middle value makes the investigation repeatable: if the dissolving time comes out close each time, you can trust it. Planning safely also means describing the risks first. Hot water can scald, so an adult handles the kettle and pours the hot water, and you read the thermometer carefully without grabbing the hot cup. You choose equipment and a setup that lets you repeat trials and keeps everyone safe.
Pick the setup that lets you repeat trials safely
You need a way to run the dissolving test three times at each temperature without a scald and without changing the sugar or water amount. Choose a setup, and see what each one gives and gives up.
How you set the cups up decides whether you can repeat the test cleanly and whether it is safe. Some setups make repeating easy and safe; others save effort now but risk a scald or change a controlled variable.
Choose a response to see what is gained and what is given up.
Permission to investigate on Country or Place
To collect water from a creek in bushland, you may need to investigate on Country or Place. This land is cared for by custodians, including the Aboriginal and Torres Strait Islander Traditional Owners. The responsible planning step is to seek permission before you go, take only what you need, and respect the land and the people who care for it. Asking permission is part of planning the investigation, just like naming the risks and setting up the equipment safely.
Which actions make the investigation repeatable, safe and properly permissioned?
A good plan has actions that make the test repeatable, actions that keep you safe, and the step of seeking permission before investigating on Country or Place. Some things you might do have nothing to do with any of these. Sort each action by whether it really helps, or whether it is beside the point.
Sort the planning actions for the dissolving investigation
The plan: time how long sugar takes to dissolve in cold, warm and hot water, using creek water collected from bushland. Decide which actions make the investigation repeatable, safe and properly permissioned, and which do not.
Claim: To investigate whether warmer water dissolves sugar faster, I should plan a repeatable, safe investigation and seek permission before working on Country or Place.
Repeat each temperature three times and take the middle value so the result is repeatable.
Seek permission from the land custodians, including the Traditional Owners, before investigating on Country or Place.
Use the same amount of sugar and water every run so only the temperature changes.
Decide which temperature will win before you have timed anything.
Have an adult pour the hot water so nobody is scalded by the kettle.
Decide whether each statement is evidence for the claim, or not.
Why this matters
Planning a repeatable investigation is what makes a result trustworthy. When you name the variable you change, the variable you measure and the variables you control, repeat your trials, describe the risks, set the equipment up safely, and seek the right permissions, your answer can be relied on. Scientists who study how substances dissolve plan their work in exactly this way.
Quick self-check
1. You test whether warmer water dissolves sugar faster. In a fair test, which is the variable you change?
2. In the same dissolving test, which is the variable you measure?
3. Why should you repeat each temperature three times instead of running it once?
4. Which variables should you keep controlled (the same) every run so the test stays fair?
5. You plan to collect water from a creek in bushland for the test. What is the responsible planning step before you go?