Skill companion: Valid, Reproducible Investigations (Year 9)

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Skill companion · Year 9 Science Inquiryseegongsik /au

Valid, Reproducible Investigations: a skill companion

A small set of reusable sheets that grow one inquiry skill: planning an investigation that measures what it means to measure, writing it so another group can repeat it and get consistent results, naming the sources of error and controlling them, and planning for safety, ethics and heritage on Country and Place. Print the scaffolds once and slot them into the science lessons you already teach.

AC9S9I02

plan and conduct valid, reproducible investigations to answer questions and test hypotheses, including identifying and controlling for possible sources of error and, as appropriate, developing and following risk assessments, considering ethical issues, and addressing key considerations regarding heritage sites and artefacts on Country/Place

What a skill companion is

Inquiry skills are not a topic of their own. They grow inside the science units a class teaches all year, from Body Systems to Chemical Equations. So this pack is not a full term of lessons. It is three reusable scaffolds, a map of where they fit, and a short stand-alone lesson for teaching the skill on its own first.

Start here: five minutes

Read the pairing map on the next page: it shows the confound, the written detail and the safety check for each topic.
Print the method writer whenever a class plans an investigation, and the results sheet when two groups have run the same method.
Cut out the cards once. They are reused all year.
Open the free interactive unit on your board when you want a worked example of the skill.
Run the one-page mini-lesson first if you want to teach the skill before folding it into a topic.

The step up from Year 8

In Year 8 a fair test changed one variable and kept the rest the same. In Year 9 that is only the start. A valid investigation controls every confound that could also change the result; a reproducible one is written so precisely that another group gets consistent numbers; and a real investigation also names its sources of error, follows a risk assessment, and treats people, animals and Country and Place with care.

On the board

This pack is the printable half of a free interactive unit. On screen, students press “Let it vary” until every line reads “Kept the same” in “Control the confounds so the wind test is valid”, weigh three choices in “Choose how many trials to run at each wind setting”, and judge each step of a plan in “Judge the plan for the wind-and-fire investigation”.

seegongsik.com/au/y9/inquiry/AC9S9I02

Aligned to the Australian Curriculum V9 (AC9S9I02). This pack is original material from seegongsik, independently produced and not endorsed by ACARA. Curriculum content descriptors are (c) ACARA, licensed under CC BY 4.0. Free to print and use in class.

Where the skill fitsPairing map

Slot the skill into your science lessons

Every investigation in the year needs the same three checks. This map shows, for one investigation in each Year 9 topic, the confound that would spoil its validity, what to write down so it can be reproduced, and the safety, ethics or Country check.

When you teach	The investigation	Valid: the confound to control	Reproducible: write down	Safe and respectful
Body Systems and Negative Feedback (AC9S9U01)	Heart-rate recovery after different skipping times	Different starting heart rates; a different skipping pace	Skips per minute, the skipping time, how the pulse is counted and for how long	Light exercise only; students with a health condition record instead
Reproduction in Animals and Plants (AC9S9U02)	Roots on cuttings left with different numbers of leaves	Different stem lengths, light or water temperature	Cutting length in cm, leaves left, days, how roots are counted	Cut away from the body; take cuttings only from school plants, with permission
The Carbon Cycle (AC9S9U03)	Indicator colour around a leaf at different lamp distances	Heat from a near lamp; leaves of different sizes	Distances in cm, the time in the light, the colour chart used	Lamps away from water; wash hands after the indicator
Wave and Particle Models of Energy (AC9S9U04)	Pulse time along a slinky stretched by different amounts	A bigger or smaller flick each time	The stretch in cm, how the pulse is started, how it is timed	Hold both ends so the slinky cannot snap back
Conservation of Energy and Efficiency (AC9S9U05)	Bounce height from different drop heights	A different ball or a different floor	Heights measured to the bottom of the ball, three drops each, the middle bounce	Clear the floor so nobody trips while watching the ball
The Atom and Radioactive Decay (AC9S9U06)	Dice left after each throw when sixes are removed	Dice that are not fair, or sixes counted in different ways	The number of dice, the removal rule, how many runs are pooled	A dice model only: no radioactive sources are used
Chemical Equations and Conservation of Mass (AC9S9U07)	Mass lost from an open cup as bicarbonate of soda fizzes in vinegar	A different vinegar, or vinegar at a different temperature	Volumes in mL, masses in g, the balance used, when the cup is weighed	Eye protection; wipe spills; never seal a fizzing bottle
Any investigation outdoors	A field study at a creek, a beach or a bush site	A change of place, weather or time of day between samples	Where and when each sample is taken, with a map	Ask about heritage before choosing the site; leave any artefact undisturbed

The three moves, and the picture that backs each one

When you want a worked example on the board, open the interactive unit and use the picture that matches the move.

Control every confound, not just the obvious one: “Control the confounds so the wind test is valid”.
Choose repeats that make a result reliable without bias: “Choose how many trials to run at each wind setting”.
Check the whole plan, safety and heritage included: “Judge the plan for the wind-and-fire investigation”.

Scaffold 1 · Method writerOne per group

A method another group could follow

NameClassDate

Write the plan so that it is valid (only the variable you test changes), reproducible (another group can follow it exactly) and safe and respectful. If a step needs a number, a unit or a rule, write it down.

Question and variables

Question How does ... affect ...?
Change (independent) and the values I will use
Measure (dependent) and its unit
Keep the same each, and how I will keep it the same

Equipment, with sizes and amounts

Steps

Number each step. Give every amount, time and reading rule. Say how many trials, and whether you will use the mean or the median.

Sources of error, and how we control them

Source of error	How we control it

Risk assessment

Hazard	What could happen	Control

People, animals and Country

Does it involve people or animals? If so: consent, care and the right to stop.No □Yes, planned □

Is the site outdoors on Country? If so: ask about heritage first; leave any artefact undisturbed.No □Yes, planned □

Scaffold 2 · Two groups, one methodOne per student

Did two groups get consistent results?

NameClassDate

A method is reproducible when another group follows it and gets consistent results. When two groups disagree, or one group’s trials scatter, the method usually has a step that can be done in more than one way.

A. The method and the results

Both groups put 150 mL of warm water in the same kind of cup and measured the temperature drop over 5 minutes, three times in still air and three times with a fan. The methods were the same except for one step.

Group A	Read the thermometer at eye level at exactly 5 minutes on the stopwatch. One person reads every trial.
Group B	Read the thermometer after about five minutes.

Group	Setting	Drops (°C), three trials
Group A	still air	6.0, 6.2, 5.9
Group A	fan	9.1, 9.4, 9.0
Group B	still air	5.1, 7.4, 6.3
Group B	fan	8.0, 10.9, 9.6

B. Do the groups agree?

By how much did the fan raise the mean drop for each group? Do the two groups agree on the fan’s effect?

C. Which trials scatter, and why?

Which group’s trials spread out more? Which step of its method could be done in more than one way?

D. Fix the step

Rewrite that step so the next group’s trials agree.

E. The swap test

Swap your own method with another group. List every step you had to guess, then give it back to be rewritten.

Scaffold 3 · Plan cards (cut out)Reuse all year

Valid, reproducible, or safe and respectful?

Cut out the cards. Lay down the three grey heading cards, then sort the plan steps under them. On the blank cards, write a step your own investigation needs for each heading.

ValidOnly the variable under test changes, so the result measures what we intend.Heading

ReproducibleWritten exactly enough for another group to repeat it and get consistent results.Heading

Safe and respectfulControls a risk to people, or respects Country and Place.Heading

Write every quantity with its unit: 100 mL of vinegar, 2 g of bicarbonate of soda, a reading every 30 seconds.Card A

Keep the volume and starting temperature of the water the same; change only the number of insulation layers.Card B

An adult fills the cups with warm water from the hot tap, never from a kettle.Card C

Drop the ball from each height three times and record the middle bounce.Card D

Use the same ball and the same hard floor at every drop height.Card E

Put a clear tank of water between the lamp and the leaf, so a nearer lamp gives more light but no extra heat.Card F

Leave any grooved rock or arrangement of stones undisturbed, and seek guidance from Traditional Owners.Card G

Write the reading rule: eyes level with the thermometer, one reader, a reading at exactly 5 minutes.Card H

Start every skipping trial from the same resting heart rate.Card I

Students with a health condition time and record instead of skipping.Card J

Use vinegar from the same bottle, at room temperature, for every mass of bicarbonate of soda.Card K

State the slinky’s stretch in centimetres, not as “quite tight”.Card L

A step that keeps my plan valid:

Write your own

A step that keeps my plan reproducible:

Write your own

A step that keeps my plan safe and respectful:

Write your own

Teacher note: the piles are not the same size. The answer sheet lists which card is which, and why.

Mini-lesson · Teacher planAbout 30 minutes

Write it so another group can repeat it

Use this stand-alone lesson to teach the skill on its own, before you fold it into a science topic. Each group writes a method for a quick test: does a fan make a cup of warm water cool faster? Then the groups swap methods and run each other’s. Any step the second group had to guess shows where the method was not reproducible. The fan and the warm cup are a safe indoor version of the wind and the camp fire in the interactive unit.

We are learning to

write a method that controls every confound, so the test is valid,
write each amount, time and reading rule, so another group gets consistent results,
name the hazards of a plan and the control for each.

Success criteria

Another group can follow my method without guessing a step.
My method lists its sources of error and its risks, each with a control.

You need

for each group: two cups of the same kind, a measuring jug, a thermometer, a stopwatch and a small fan (cord and plug well away from the water); warm water from the hot tap (an adult fills the cups; not from a kettle),
the method writer (scaffold 1), one per group, and the cards from scaffold 3, one set per table. Wipe up spills straight away.

Lesson flow (about 30 minutes)

5 min	What could go wrong? Show the board (see the box). Ask: “If the fuel and the wind both change, what can the result tell us?”
10 min	Write the method Groups fill the method writer for the fan test: amounts, times, the reading rule, repeats, error and risk. Ask: “Which step could two people do in two different ways? Write a rule for it.”
10 min	Swap and run Groups swap methods and run the other group’s exactly as written, marking any step they had to guess. Each group writes its result on the board. While the water cools, tables sort the cards. Ask: “Which groups got results close together? What was different about their methods?”
5 min	Fix the guesses Methods go back to their writers, who rewrite each guessed step with a number, a unit or a rule.

Running it shorter? Stop after writing the method, and swap and run in your next science lesson.

On the board

For a worked example, open the unit and press “Let it vary” on each line of “Control the confounds so the wind test is valid” until every line reads “Kept the same”. Then try the three choices in “Choose how many trials to run at each wind setting”.

seegongsik.com/au/y9/inquiry/AC9S9I02

Watch for these ideas

Thinking a method is reproducible because the writers understand it: the test is whether someone else can follow it.
Repeating trials but changing the method between them.
A risk assessment that names hazards with no control beside them.

Make it easier, make it bigger

Easier: give the first two steps written out, and ask groups to write the rest in the same way.
Bigger: add a third setting (the fan on high) and decide how many trials each setting needs.

Answers and look-fors

The next sheet has the card key, the worked results of the two groups, a method at standard for the fan test, and a quick three-level guide.

Answers · For the teacherModel responses

Answers and look-fors

Plan cards

Card	Plan step	Pile	Why
A	Write every quantity with its unit: 100 mL of vinegar, 2 g of bicarbonate of soda, a reading every 30 seconds.	Reproducible	Another group can measure out exactly the same.
B	Keep the volume and starting temperature of the water the same; change only the number of insulation layers.	Valid	Only the layers differ, so the result is about the layers.
C	An adult fills the cups with warm water from the hot tap, never from a kettle.	Safe and respectful	Controls the risk of scalds.
D	Drop the ball from each height three times and record the middle bounce.	Reproducible	A written rule for repeats that the next group follows too.
E	Use the same ball and the same hard floor at every drop height.	Valid	A different ball or floor would change the bounce as well as the height.
F	Put a clear tank of water between the lamp and the leaf, so a nearer lamp gives more light but no extra heat.	Valid	Removes heat as a second change, so only the light differs.
G	Leave any grooved rock or arrangement of stones undisturbed, and seek guidance from Traditional Owners.	Safe and respectful	Respects cultural heritage on Country and Place.
H	Write the reading rule: eyes level with the thermometer, one reader, a reading at exactly 5 minutes.	Reproducible	A rule every group can follow, so readings do not depend on who looks or when.
I	Start every skipping trial from the same resting heart rate.	Valid	Each recovery starts from the same place, so only the skipping time differs.
J	Students with a health condition time and record instead of skipping.	Safe and respectful	Controls a risk to a person’s health.
K	Use vinegar from the same bottle, at room temperature, for every mass of bicarbonate of soda.	Valid	A stronger or warmer vinegar would change the mass lost as well.
L	State the slinky’s stretch in centimetres, not as “quite tight”.	Reproducible	A number another group can set; “quite tight” means different things to different people.

Two groups, one method

Group A: still air mean 6.03, range 0.3; fan mean 9.17, range 0.4. Group B: still air mean 6.27, range 2.3; fan mean 9.50, range 2.9 (all in °C). The fan raised the mean drop by 3.14 °C for Group A and 3.23 °C for Group B, so the groups agree on the size of the effect. But Group B’s trials scatter far more (ranges 2.3 and 2.9 against 0.3 and 0.4): its step “after about five minutes” let each trial be read at a different time, by a different reader. A fix: “read the thermometer at eye level at exactly 5 minutes; one person reads every trial”. Trials that scatter by more than 2 °C could not show a smaller effect, such as a gentler fan’s.

A method at standard for the fan test

An adult pours 150 mL of warm water from the hot tap into the cup. Stir, and start when the thermometer reads 45 °C.
Still-air trials: the fan stays off. Fan trials: the fan is on low, 50 cm from the cup, pointing at it.
Start the stopwatch as the water reaches 45 °C.
At exactly 5 minutes, read the thermometer at eye level. The same person reads every trial. Work out the drop.
Run three trials at each setting, with fresh water each time, and report the median drop.

Source of error	Control	Hazard	Control
Different readers, different reading times	one reader, eyes level, at exactly 5 minutes	Warm water	an adult pours; cups stand on a tray
Water starting at different temperatures	start every trial at 45 °C	A fan near water	cord and plug well away from the cups; dry hands
A draught from a door or window	run every trial at the same bench, doors closed	Spills on the floor	wipe them up at once

A quick three-level guide

Move	Working towards	At standard	Beyond
Valid	keeps one variable the same, but misses other confounds	controls every confound that could also change the result	explains how an uncontrolled confound would have misled the conclusion
Reproducible	writes steps another group has to guess at	gives every amount, time and reading rule, with repeats	checks the method with a swap test and fixes each guessed step
Safe and respectful	names hazards with no controls	pairs each hazard with a control, and checks people, animals and Country	plans ahead for heritage on Country and Place before choosing a site

A student at standard writes a method another group can follow without guessing, with its confounds, errors and risks each paired with a control. The skill grows all year, so bring the method writer back to every investigation.