Experimental design questions in VCE Chemistry are often misunderstood as practical recall questions. Students assume they are being assessed on whether they remember school-based experiments or generic laboratory procedures. The 2024 Chemistry exam and the accompanying Examiner’s Report show very clearly that this is not what is being assessed.
Instead, experimental design questions are used to test whether students can reason scientifically under constraint. They reward students who can read an unfamiliar method, identify what the experiment is attempting to measure, and evaluate whether the design achieves that aim.
Experimental design questions assess thinking, not experience
One of the clearest patterns in the 2024 Examiner’s Report is that students with extensive practical experience did not automatically perform better on experimental design questions.
Many responses described plausible laboratory procedures but failed to address the specific experimental aim given in the question. These responses were often fluent and confident, yet capped.
The exam is not asking whether a method would work in a general sense. It is asking whether the method works for the stated purpose. Any discussion that does not explicitly reference that purpose is incomplete.
Identifying the independent and dependent variables is not optional
A recurring issue noted in the 2024 Examiner’s Report is that students launched into evaluation without first establishing what was being changed and what was being measured.
In multi-part questions, early marks are often allocated to recognising variables, either explicitly or implicitly. Students who misidentified the dependent variable often carried this error through subsequent parts of the question.
This is why experimental design questions are unforgiving. A misreading early on affects every later judgement.
High-scoring responses always demonstrated, either directly or indirectly, that the student understood:
- what variable was deliberately changed
- what variable was measured in response
Without this, evaluation becomes guesswork.
Control of variables must be relevant, not exhaustive
Another common error highlighted in the Examiner’s Report was students listing large numbers of controlled variables without explaining why they mattered.
For example, students wrote that temperature, pressure, volume, and concentration should be controlled, regardless of whether these variables were relevant to the experimental aim.
These responses were often capped because they demonstrated rote learning rather than reasoning.
The exam rewards relevance. Controlling a variable earns credit only if the student explains how variation in that variable would affect the outcome being measured.
Experimental improvements must address the actual weakness
One of the most discriminating parts of experimental design questions is the request to suggest an improvement.
In the 2024 exam, many students suggested adding repeats, using more precise equipment, or increasing sample size. While these suggestions are not wrong in isolation, the Examiner’s Report makes it clear that they were not always appropriate.
Marks were awarded only when the suggested improvement directly addressed a specific limitation in the original design.
For example, suggesting repeats does not improve accuracy if the issue is systematic error. Suggesting more precise equipment does not improve validity if the experiment is measuring the wrong variable.
High-scoring responses identified the weakness first, then proposed a targeted improvement.
Validity is often the hidden focus
Although validity is not always named explicitly, it is frequently the underlying focus of experimental design questions.
In the 2024 exam, several design questions required students to consider whether the method actually tested the hypothesis being investigated. Many students focused on measurement quality rather than experimental alignment.
The Examiner’s Report notes that responses which addressed precision or reliability without discussing whether the design isolated the intended variable were capped.
This is a subtle but crucial distinction. Validity questions require students to think about what the experiment proves, not just how well it was performed.
Students often describe procedures instead of evaluating them
Another pattern identified in the 2024 Examiner’s Report is descriptive drift.
When asked to evaluate or justify aspects of an experimental design, many students rewrote the method in different words rather than analysing it. These responses earned little credit because they did not address strengths, limitations, or consequences.
Experimental design questions are not asking for a summary of what was done. They are asking whether what was done was appropriate.
Why students struggle with these questions under exam conditions
Experimental design questions feel uncomfortable because they are unfamiliar. Students cannot rely on memorised answers or standard equations. They must read, decide, and judge.
Under pressure, many default to writing everything they know about experiments. This produces long responses that lack focus.
The 2024 Examiner’s Report shows that concise, targeted responses consistently outperformed longer, unfocused ones.
What full-mark responses consistently demonstrated
Across the 2024 paper, high-scoring experimental design responses shared several features.
They:
- identified the aim of the experiment clearly
- showed understanding of variables without necessarily naming them explicitly
- evaluated design choices in relation to that aim
- proposed improvements that addressed specific weaknesses
- used accuracy, reliability, or validity correctly and contextually
These responses were rarely verbose. They were deliberate.
How students should be practising experimental design
Improvement in this area does not come from doing more practical work. It comes from practising evaluation.
Students should practise:
- reading unfamiliar methods and identifying the aim
- deciding what the experiment can and cannot conclude
- matching flaws to appropriate evaluative terms
- proposing targeted, justified improvements
This mirrors exactly how marks are allocated.
An ATAR STAR perspective
ATAR STAR teaches experimental design as an analytical skill rather than a practical one. Students learn how examiners read these questions and how to respond efficiently and accurately under time pressure.
This approach consistently lifts Chemistry results because experimental design questions appear every year and are rarely answered well by default.
In VCE Chemistry, experimental design is not about what you did in the lab. It is about how well you can think like a chemist in the exam.