VCE Physics practical investigation structure: the 2026 guide

What this guide is for

The VCE Physics Unit 4 student-designed practical investigation is one of the major SACs. Students design, conduct, and report on an original investigation. The poster format requires disciplined attention to all aspects of scientific method. This guide covers the structure, marking criteria, and the moves that secure Band 6.

Poster structure

Standard sections (A1 size, around 600-1000 words):

1. Title. Specific, descriptive.
2. Research question. One sentence.
3. Hypothesis. Predicted relationship with theoretical justification.
4. Variables. Independent (range, measurement method, precision), dependent (measurement method, precision), controlled (with rationale).
5. Methodology. Labelled diagram of setup; step-by-step procedure; justification of design choices.
6. Risk assessment. Identified hazards and mitigation.
7. Data tables. Raw and processed, with units and uncertainties.
8. Graphs. Linearised where applicable; uncertainty bars; best-fit line.
9. Analysis. Gradient, intercept, derived quantities with uncertainty.
10. Discussion. Uncertainty sources, limitations, suggested improvements, comparison to theory.
11. Conclusion. Direct answer to research question.
12. References.

Research question

Form: "How does [IV] affect [DV] for [system] with [controlled variables] held constant?"

Good examples:

• How does the length of a simple pendulum affect its period?
• How does the slit separation affect the fringe spacing in a Young's double-slit setup?
• How does the inclination of an inclined plane affect the acceleration of a cart down the plane?

Each has a measurable IV, a measurable DV, and a clear system.

Hypothesis

Should be specific. "Period will increase as length increases" is weak; "Period will be proportional to $\sqrt{L}$ (so a plot of $T$ against $\sqrt{L}$ will be linear with gradient $2\pi/\sqrt{g}$)" is strong.

Include the theoretical basis. The marker should see that the hypothesis arises from theory, not just intuition.

Variables and method

For each variable:

• Range (e.g., 5 to 45 degrees in 5-degree steps).
• Measurement method (e.g., protractor with 1 degree precision).
• Number of trials per IV value (typically 3-5).
• Why each controlled variable matters.

The methodology should include a clear labelled diagram. Step-by-step procedure must be detailed enough to replicate.

Uncertainty

Random uncertainty. From measurement-to-measurement variability. Estimate by half-range or standard deviation of repeated measurements.

Systematic uncertainty. From instrument bias (zero error, calibration). Estimate from instrument specifications.

Instrumental uncertainty. Half the instrument precision (typically).

Propagation rules.

• Addition/subtraction: add absolute uncertainties.
• Multiplication/division: add fractional uncertainties.
• Powers: multiply fractional uncertainty by the power.

Reporting. Value ± uncertainty, both to consistent decimal places.

Linearisation

Many physics relationships are non-linear. Linearise before plotting:

• IMATH_4 : plot $y$ vs $x^2$.
• IMATH_7 : plot $y$ vs $1/x$.
• IMATH_10 : rearrange to $T^2 = (4\pi^2/g) L$. Plot $T^2$ vs $L$, gradient $4\pi^2/g$.

Linearisation lets you fit a straight line and extract a meaningful gradient.

Gradient and uncertainty

Best-fit line: standard linear regression through the data.

Gradient uncertainty: draw a max-slope line (steepest line through error bars) and a min-slope line (shallowest). The half-range of these slopes is the uncertainty in the gradient.

Discussion

Strong discussion sections:

Uncertainty sources. Name specific sources tied to specific steps. Random vs systematic distinction. Major contribution vs minor.

Limitations. What the investigation cannot conclude. Are controlled variables truly constant? Is the range of the IV sufficient? Is the data sufficiently varied?

Improvements. Specific changes that would reduce uncertainty or extend the result. Use a longer pendulum; use a photogate instead of stopwatch; use more trials per IV value.

Comparison to theory. Calculate the predicted value; compare experimental result within uncertainty. State whether the result supports the hypothesis.

Conclusion

A direct answer to the research question. Concise. Include the experimental value with uncertainty, and the comparison to the accepted value within uncertainty.

Marking criteria

VCAA's published criteria reward:

1. Investigation design. Quality of research question, hypothesis, methodology.
2. Quality of data. Range, precision, repeats.
3. Analysis. Linearisation, gradient extraction, uncertainty handling.
4. Discussion. Sophisticated treatment of uncertainty, limitations, improvements.
5. Scientific communication. Poster design, scientific writing.

Top band requires excellence in all five.

In one sentence

The VCE Physics Unit 4 student-designed practical investigation is a poster-formatted report on an original experiment, with sections covering research question, hypothesis, methodology, data, analysis (with uncertainty propagation and linearisation), discussion (uncertainty sources, limitations, improvements, comparison to theory) and conclusion; Band 6 posters demonstrate sophisticated uncertainty handling (random vs systematic, gradient uncertainty from min/max lines), explicit linearisation of non-linear relationships, and a discussion that names specific uncertainty sources tied to specific experimental steps.