How Do You Build a Risk Assessment for a School Science Investigation?

A toy car rolls down a ramp in a school science lab. You’re measuring how far it travels across different surfaces, but there’s a problem: the smoothest surface might let the car roll straight off the bench.

Would writing “be careful” in your risk assessment solve that problem? No. You need to identify exactly what could go wrong, how someone might be harmed, and what would prevent it.

To build a risk assessment for a school science investigation, describe your proposed method, identify hazards at every stage, assess the likelihood and consequences of harm, select suitable control measures, and record any remaining risks. Then check your school’s safety procedures and obtain teacher approval before starting practical work.

The goal isn’t to prove that an experiment has no risks. It’s to decide whether those risks can be properly controlled, or whether the investigation needs to change.

01Start by picturing the entire investigation

Imagine you’re investigating how different surfaces affect the stopping distance of a toy car.

Your proposed apparatus has a short ramp at one end of a bench. The car rolls down the ramp, travels across a horizontal test surface, and eventually stops. You measure the distance travelled along that surface.

What should the experiment show?

If the release conditions stay the same, you may find that the car travels different distances on different surfaces. That gives you evidence about how the surfaces affect its motion.

Now picture the smoothest surface. What happens if the car doesn’t stop before reaching the end of the bench?

That’s a safety problem you can identify without running the experiment.

This is how a useful risk assessment begins: by mentally following the experiment from preparation to disposal or pack-up, rather than immediately filling in a table.

Describe what will actually happen

Before listing hazards, write enough about the proposed method to make the arrangement clear.

Record:

• Materials and equipment: Exactly what will be used, including the identity and quantities of any substances.
• Location: The classroom, laboratory, or fieldwork area, including nearby people and equipment.
• Actions: What happens during set-up, measurements, changes between trials, and clean-up.
• People: Who will operate the equipment, who will observe, and who else could be affected.
• Changes: Which variable will change between trials and whether that change affects the hazards.
• Supervision: What teacher involvement, equipment checks, and permissions are needed.

For the toy-car investigation, this means considering the ramp, car, test surface, bench, measurement area, and walkway.

It also means considering what happens when students change surfaces or retrieve the car between trials.

A risk assessment written only for the moment when the car is moving would miss part of the investigation.

02Identify hazards, risks, and consequences

Three terms are worth separating.

A hazard is something with the potential to cause harm.

A risk concerns the possibility that harm will occur through exposure to that hazard.

A consequence is the harm that could result.

Think about a bag left in a walkway. The bag is the hazard. Someone tripping over it is the risk event. A sprained ankle is one possible consequence.

The same distinction works in a science lab.

Notice that the consequence isn’t always predictable from the hazard alone.

A small quantity of a substance isn’t automatically harmless. A low-voltage device isn’t automatically suitable for every location. The equipment, conditions, and people involved all affect the risk.

Assess likelihood and severity

Once you’ve identified a hazard, consider two questions:

1. How likely is someone to be harmed under the proposed conditions?
2. How serious could that harm be?

You might describe the likelihood as unlikely, possible, or likely, and the consequence as minor, moderate, or severe.

Your school may provide a risk matrix with more specific categories or numerical ratings. Use that system if required.

Don’t invent probability percentages or choose ratings simply to make the experiment appear acceptable. A matrix is a decision aid, not a measurement of the exact chance of an accident.

You should also assess the risk remaining after controls have been applied. This is called residual risk.

03Choose controls that address the hazard

Return to the toy-car investigation.

A student might suggest wearing safety glasses in case the car flies off the bench.

That may sound cautious, but it doesn’t prevent the car from leaving the track or protect someone’s feet.

A stronger approach is to redesign the arrangement so the moving car remains inside a secured, designated testing area.

This follows the hierarchy of controls: remove or reduce hazards at their source before relying on instructions or personal protective equipment.

The main control options are:

These options aren’t interchangeable. A physical guard may prevent something that a verbal warning cannot.

SafeWork NSW explains the hierarchy of risk controls, including why eliminating a hazard is generally more reliable than depending entirely on human behaviour.

An annotated risk assessment entry

Here’s how the revised toy-car investigation could be recorded.

This is an illustration, not a completed school-authorised assessment.

There’s also a scientific complication. If the car hits the end barrier, that barrier stops it. The measured distance is no longer its unrestricted stopping distance on the test surface.

A safer arrangement must still allow you to collect meaningful evidence.

04Chemical investigations need an additional check

Now consider a different investigation.

You’re comparing the pH of three aqueous samples supplied and labelled by your science teacher. The proposed method uses teacher-approved indicator strips, a designated laboratory bench, and the school’s arrangements for handling and disposal.

A classmate suggests adding a fourth sample from an unlabelled bottle at home.

Predict the problem. The new liquid might turn out to be relatively harmless, so why not include it?

Because you don’t yet know what it contains, its concentration, or whether its use is permitted.

The original assessment covered the identified school-supplied samples, not every liquid someone might bring into the laboratory.

For chemicals, relevant information may include:

• The actual identity and concentration of the substance.
• Its container label and safety data sheet (SDS), where applicable.
• The school’s permitted-use restrictions and approved controls.
• Whether students are allowed to handle it.
• Requirements for storage, supervision, and disposal.

A safety data sheet provides information about a substance’s hazards and handling requirements. It doesn’t automatically authorise students to use that substance.

For NSW public schools, the Department of Education’s Chemical Safety in Schools guidance sets out chemical risk assessment processes and restrictions. Teachers and authorised staff must apply those procedures; students shouldn’t decide chemical permissions independently.

05What NSW rules and school procedures actually require

There’s a difference between what the syllabus expects you to learn and who has authority to approve practical work.

NESA: scientific investigation and syllabus requirements

The NSW Education Standards Authority (NESA) includes planning and conducting scientific investigations within Working Scientifically.

That includes making informed decisions about suitable methods and safety.

The NSW Department of Education’s science safety and compliance guidance connects student risk assessment to planning investigations and provides a risk assessment scaffold.

NESA does not personally approve each student’s laboratory procedure. The school manages its practical activities under applicable safety obligations and procedures.

Syllabus editions also differ by cohort. As at 10 November 2026, the Physics 11-12 Syllabus (2025) begins implementation for Year 11 in 2027, with its first HSC examination in 2028. The Chemistry 11-12 Syllabus (2025) begins for Year 11 in 2028, with its first HSC examination in 2029.

Students should use the syllabus applicable to their cohort, but the need to manage practical risks doesn’t disappear during a syllabus transition.

NSW Department of Education: public school safety procedures

NSW public schools must follow the Department’s applicable safety procedures.

Its Chemical Safety in Schools guidance explains how authorised staff assess chemical hazards, determine controls, and apply departmental restrictions.

The Department’s guidance for student-designed chemical investigations also makes clear that hazardous chemical activities require appropriate teacher assessment, instructions, and approval. A depth study doesn’t provide an exemption.

These particular departmental procedures apply to NSW government schools. Non-government schools have their own applicable safety procedures and approval arrangements.

Your school: the procedure you must actually follow

Your teacher or science faculty can tell you:

• Which risk assessment form or digital system to use.
• Whether your proposal needs review by a laboratory technician, head teacher, or another authorised person.
• Which equipment, substances, and locations are permitted.
• What supervision, protective equipment, emergency arrangements, and disposal procedures apply.
• Whether additional approval is needed for fieldwork or activities outside ordinary lessons.

A teacher may reject an investigation even if a student believes the risk is low. Permission depends on the actual method, available facilities, and applicable school requirements.

Don’t begin an unapproved practical activity, or move hazardous experimental work home, simply because it is part of a school assessment.

06A decision process you can use before submitting

A good risk assessment should help someone make a decision, not just record hazards after the decision has already been made.

Use this sequence.

1. Is the proposed activity allowed?

Check whether the materials, equipment, location, and proposed activities meet school requirements.

If a substance is unidentified, a restriction is unclear, or the activity needs specialist supervision that isn’t available, stop planning that version until the teacher resolves the issue.

2. Can you remove the hazard?

Look for a safer arrangement that still addresses your investigation question.

For example, could the question be answered with approved lower-risk materials, a different measuring method, or suitable existing data?

3. Can remaining risks be controlled?

Explain what the control physically does and who is responsible for making it work.

“Use a secured barrier checked by the teacher” is more useful than “take care”.

4. Does the safer method still answer the question?

A protective measure can change what you measure.

If adding a lid prevents the evaporation you’re trying to investigate, the method may be safer but scientifically unsuitable.

5. Has the teacher reviewed the complete plan?

Submit the method and risk assessment together.

Include the control measures, residual risks, supervision needs, and any unresolved questions.

6. What happens if conditions change?

An approved plan isn’t permission to improvise.

If equipment fails, an unexpected hazard appears, or you want to change a substance, location, or procedure, stop the affected activity and tell the teacher. The risks and approvals must be reviewed as appropriate.

A final checklist

Before handing in your assessment, confirm that:

• [ ] The investigation method is specific enough for another person to understand.
• [ ] Hazards are considered during preparation, testing, changes between trials, and clean-up.
• [ ] The people who could be harmed are identified.
• [ ] Likelihood and consequence have been assessed using the school’s method.
• [ ] Controls address the actual hazards, rather than relying on vague warnings.
• [ ] Remaining risks and any limitations are recorded.
• [ ] Materials and activities comply with applicable school procedures.
• [ ] The controls don’t invalidate the measurements.
• [ ] Teacher review and approval are obtained before practical work.
• [ ] Changes, unexpected hazards, and incidents will be reported through the school’s procedures.

07Questions and solutions

Try each question before reading its solution. The first is a straightforward application; the later questions require you to judge competing controls, changing conditions, and what the evidence can actually support.

Question 1

A student proposes rolling a small toy car down a ramp on a classroom bench. The track ends near a walking aisle.

Identify one hazard, explain one possible consequence, suggest two suitable control measures, and state who should authorise the practical investigation.

Solution 1

The main hazard is the car leaving the bench and entering an area used by people. It could strike someone or create a trip hazard.

Two suitable controls to propose are:

1. Use a teacher-checked, secured track with an appropriate end barrier, so the car remains within the testing area.
2. Keep the testing area separated from the walkway and prevent students from entering the car’s path during trials.

These controls act on the hazard and people’s exposure, rather than relying only on instructions to be careful.

The supervising science teacher must review and authorise the proposed activity, with any additional checks required by the school.

Question 2

A student has approval to compare evaporation from two identical open containers of water under the same classroom conditions.

After noticing that evaporation is slow, the student proposes moving one container to a sunny outdoor table and leaving the other indoors. The student argues that the assessment is still valid because both containers contain only water.

Evaluate the proposed change in terms of safety, experimental validity, and approval. Suggest a better next step.

Solution 2

The student should not make the change under the original approval. Moving one container outdoors changes both the risk conditions and the variables affecting evaporation.

First, the outdoor location introduces considerations that weren’t necessarily part of the original assessment, including weather, public access, stability of the equipment, and supervision. The teacher must assess whether the new setting is suitable and permitted.

Second, the investigation no longer provides a controlled comparison. The containers could experience different temperatures, air movements, and humidity. If one loses more water, the student couldn’t confidently attribute the difference to sunlight alone.

The tempting argument is that unchanged materials mean unchanged risk. But location and environmental conditions are also part of a risk assessment.

A better next step is to discuss the slow evaporation with the teacher. They can consider an approved method that keeps relevant conditions comparable, or an alternative investigation using suitable existing data.

The student shouldn’t introduce new equipment or environmental conditions independently to speed up the result.

Question 3

A class of 24 students is organised into six groups of four. Each group has four planned toy-car trials.

The proposed investigation uses six tracks, but the science laboratory has only two suitable bench positions where the tracks can be secured away from walkways.

One student suggests moving all six tracks into the corridor to collect data simultaneously. Another suggests using the two suitable bench positions and rotating groups through them.

Each track has an appropriate teacher-approved end barrier.

Compare the proposals. Explain why the number of tracks alone doesn’t determine risk, and identify the conditions that would need to be met before the preferred arrangement could proceed.

Solution 3

Rotating groups through the two suitable laboratory positions is the more defensible proposal, provided the teacher confirms that supervision, movement, and access can be managed safely.

The corridor proposal creates new concerns. The tracks could obstruct pedestrian movement, interfere with access, and expose people who aren’t participating in the investigation. The original classroom assessment wouldn’t automatically cover these conditions.

The total number of planned car runs is:

\[ \begin{aligned} N &= 6 \times 4\\ &= 24\text{ runs} \end{aligned} \]

Both arrangements involve 24 planned runs. Reducing the number of tracks from six to two doesn’t eliminate those runs; it reduces the number of simultaneous operating stations.

That can make the activity easier to supervise and separate from other students, but only if the rotation is organised properly.

The two-track plan would need to establish that:

• The tracks and barriers are suitable for the proposed trials.
• Walkways and exits remain clear.
• Waiting students are kept away from operating tracks.
• Equipment changes and movement between groups are supervised.
• The arrangement is authorised by the teacher and meets school procedures.

There’s a second scientific benefit if the same two tracks are used consistently: fewer differences between pieces of equipment may reduce unwanted variation in measurements.

However, the tracks still need to provide comparable release and measurement conditions.

The subtle mistake is assuming that fewer pieces of equipment automatically produce lower total risk. Risk also depends on the number of people exposed, their movement, the arrangement, and whether controls remain effective throughout the activity.

Question 4

A Physics student wants to investigate how the electrical behaviour of a filament lamp changes as its operating conditions change.

The school has a supervised, enclosed teaching apparatus, but the teacher decides that the student’s proposed independent practical method will not be approved.

The student makes two alternative proposals:

• Proposal A: Use a computer simulation that assumes the filament’s resistance increases with temperature, then claim that the results experimentally prove resistance increases with temperature.
• Proposal B: Use a documented dataset collected previously with suitable equipment, compare the observed pattern with a physical model, and explain the limitations of the data.

Which proposal gives stronger evidence for the original scientific claim? Explain the role of risk assessment, the limitation of the simulation, and what still requires teacher approval.

Solution 4

Proposal B provides stronger evidence for the original scientific claim because it uses observations that can be compared with a physical model. Proposal A may be useful for learning, but it cannot independently prove an assumption built into the simulation.

The teacher’s decision not to approve the student’s independent practical method is a safety constraint. The student must respect that decision rather than attempting the experiment elsewhere or with an improvised apparatus.

For Proposal A, the reasoning is circular. If the software is programmed so that resistance increases with temperature, a graph showing that relationship demonstrates the behaviour of the model.

It doesn’t establish that the physical relationship is true.

Proposal B can provide empirical evidence, provided the student checks the source, apparatus description, measured variables, operating conditions, and uncertainties. A dataset with missing or unsuitable information may not support the desired conclusion.

The student could also compare the simulation’s prediction with the independent dataset. Agreement would support the model within the conditions represented by the data, without proving that the model is universally correct.

Both alternatives still need the teacher’s agreement as suitable methods for the school investigation or assessment.

The deeper principle is that changing a method for safety may also change the kind of scientific evidence available. A simulation can be a valid investigation tool, but its assumptions must not be mistaken for experimental findings.

Question 5

A student is investigating how three surfaces affect the unrestricted stopping distance of the same toy car.

The teacher-approved apparatus has a secured ramp, a horizontal test track, and a protective end barrier 1.20 m from the beginning of the horizontal section. All trials use the same car and the same release point.

In a hypothetical supervised pilot, the following results are recorded:

The student proposes three ways to complete the dataset:

• Plan A: Record 1.20 m as the stopping distance on the polished surface.
• Plan B: Move the barrier farther along the track, into an adjacent walkway.
• Plan C: Lower the car’s release point for the polished surface only, so that it stops before the barrier, and compare that result with the original two measurements.

Another student argues that the polished-surface trial is completely useless because the car never stopped freely.

Answer all parts:

(a) What can be concluded from the original three observations, and what remains unknown?

(b) Evaluate Plans A, B, and C, considering both safety and experimental validity.

(c) Propose a defensible way to obtain a complete numerical comparison, and explain what must happen before that revised investigation can proceed.

Solution 5

The original results establish that the polished-surface car travelled farther than the other two cars under the tested conditions, but they don’t establish its unrestricted stopping distance. None of Plans A, B, or C provides a valid complete comparison as proposed.

(a) What the observations actually show

On rough fabric, the measured stopping distance was 0.73 m.

On smooth plastic, it was 0.91 m.

On the polished surface, the car was still moving when it reached the barrier at 1.20 m. Therefore, assuming the barrier was the first object that interrupted its motion, its unrestricted stopping distance would have exceeded 1.20 m under those release conditions.

We can express the information as:

\[ \begin{aligned} d_{\text{rough}} &= 0.73\text{ m}\\ d_{\text{smooth}} &= 0.91\text{ m}\\ d_{\text{polished}} &> 1.20\text{ m} \end{aligned} \]

Here, \(d\) represents the unrestricted stopping distance on each surface.

This gives a valid ordering:

\[ d_{\text{rough}} < d_{\text{smooth}} < d_{\text{polished}} \]

But it doesn’t give the exact value of \(d_{\text{polished}}\).

This is the first important twist. The polished-surface observation isn’t useless.

It provides a lower bound, even though it doesn’t provide a complete measurement.

(b) Evaluating the proposed plans

Plan A is scientifically invalid.

The barrier stopped the car. The student’s target measurement is the distance the car would travel before stopping without that intervention.

Recording 1.20 m as its unrestricted stopping distance would confuse the limit of the apparatus with the behaviour of the car.

The student has measured where the barrier is, not where the car would naturally stop.

Plan B requires a new safety assessment and is not acceptable as an independent modification.

Moving the barrier into a walkway changes who could be exposed to the moving car and may create an obstruction.

It also changes the arrangement that the teacher originally approved.

A longer measurement area could be scientifically helpful, but it must be appropriately designed, located, controlled, and authorised. Simply moving equipment into an unsuitable space isn’t a solution.

Plan C creates an unfair comparison.

Lowering the release point changes the car’s starting conditions. It would generally change the car’s speed and kinetic energy when it reaches the horizontal section.

The original two distances were measured using a different release point.

A shorter distance on the polished surface under the new conditions wouldn’t necessarily mean that the polished surface produced more resistance.

The student would be changing both the test surface and an important starting condition.

(c) A defensible revised investigation

One possibility is to ask the teacher whether a lower common release point can be used for all three surfaces, with the original protective arrangements maintained.

If the teacher determines that this is suitable and the revised release conditions allow all three cars to stop freely within the measurement area, the student can collect a new comparable set of results.

Every surface must be tested under the same revised starting conditions.

The student should not mix the original stopping distances with the new measurements as though all trials used the same method.

The teacher must review the revised arrangement, its controls, and the resulting residual risks before authorising the change. If suitable measurements cannot be obtained within an approved arrangement, the student should change the investigation scope or use an appropriate alternative source of data.

Why this question is harder than it first appears

There are two separate boundaries.

The safety boundary determines which experimental arrangements are acceptable.

The measurement boundary determines what conclusions the evidence supports.

The original barrier makes the arrangement safer, but it also limits the measurement. Removing or relocating it could compromise safety. Changing the release condition for only one surface would compromise the comparison.

The correct response isn’t to ignore the inconvenient result or force the experiment to produce a number.

It’s to preserve the valid information already obtained, identify exactly what remains unknown, and redesign the investigation within approved safety conditions.

08What comes after the risk assessment?

An approved risk assessment gives you a set of conditions under which the proposed investigation may proceed. It doesn’t guarantee that the experiment will produce useful results, and it doesn’t replace supervision.

The next task is checking that your method measures what you intend, that relevant variables are controlled, and that any changes are recorded honestly.

That’s where risk assessment connects with Working Scientifically in HSC Physics and Chemistry: planning, carrying out, and evaluating an investigation are linked decisions.

If your investigation forms part of a depth study in HSC Science, its safety plan should be developed alongside the research question and method, rather than added after the experiment has already been designed.

The practical decision is simple: if a hazard cannot be adequately controlled under the school’s requirements, change the method before collecting data. A smaller, well-controlled investigation can provide stronger scientific evidence than a more ambitious experiment whose safety or measurements cannot be justified.