QCE Chemistry IA2 student experiment: how to get top marks

Your IA2 is worth 20% of your final result and is marked out of 20: five marks each across four criteria, Forming, Finding, Analysing, and Interpreting and Evaluating. The difference between a middle-band and a top-band mark in every one of them comes down to a small set of adjectives, considered against reasonable, justified against feasible, thorough against basic. This guide works through what each criterion actually wants, using QCAA's own wording and its published examples of marked student work.

This guide describes the Chemistry 2025 v1.0 syllabus, which applies to Year 11 from 2025 and Year 12 from 2026, so the 2026 Year 12 cohort is the first assessed under it. The exemplars quoted below come from the four subject reports published so far (2022 to 2025 cohorts), all marked under the superseded Chemistry 2019 v1.3 ISMG. Their criterion names and mark splits describe the old rules, but the advice about what separates a strong response from a weak one is about chemistry and data, not about criterion labels, so it survives the revision.

What the task actually asks

You modify an experiment relevant to Unit 3: refine, extend or redirect a practical you have already done, to address your own related research question. QCAA designs the task around roughly 10 hours of class time.

The task covers identifying an experiment to modify, developing a research question, researching the science behind it, conducting a risk assessment, running the experiment, collecting and processing data, analysing it for trends and for uncertainty and limitations, drawing a conclusion, evaluating reliability and validity, and suggesting improvements and extensions. All six assessment objectives are assessed here, unlike the external exam, which only examines four.

Conditions. Written up to 2000 words, or multimodal up to 11 minutes with at least two modes delivered at the same time.

What can be done as a group: identifying the experiment, developing the research question, conducting the risk assessment, running the experiment, and collecting data. Processing, analysing, interpreting and writing it up are yours alone.

Forming (5 marks)

Marked on your rationale, your modifications, your research question, and your use of genre, referencing and scientific language.

Both genre and referencing conventions and scientific language sit inside Forming for IA2. Do not carry that across to IA3, which splits them: referencing and scientific language go into Forming and Finding there, and genre conventions move to Evaluating. See the IA3 research investigation guide.

For modifications, "changed the equipment" is not enough on its own. QCAA's model, used in two separate reports: changing filter paper to a glass U-shaped salt bridge, "as it allows for a more efficient ion transfer." The modification is named, and the reason it matters is stated in the same sentence.

Finding (5 marks)

Marked on your management of risks, ethical and environmental issues, and on the raw data you collect.

The only thing separating the bands here is the word considered: the top band asks for considered management of risks, ethical and environmental issues, the middle band just for management of them. The reports held give no Chemistry example of what QCAA counts as considered, so treat the adjective as the instruction it is and tie each precaution to your own procedure.

Analysing (5 marks)

Marked on how you process your data and what you find in it.

Named in three of the four reports held (2022, 2023, 2025) in near-identical wording, this is the single most repeated IA2 marking message: identify uncertainty and limitations from the evidence itself, not from a discussion of your methodology. QCAA's own phrasing: uncertainty and limitations "thoroughly identified through systematic and effective analysis of the evidence," and not by "discussing problems relating to methodology."

QCAA's own worked examples of processing real data: calculating mean cell potential, percentage uncertainties and percentage error to identify uncertainty; scatter graphs with an appropriate line of best fit and error bars to identify trends; linearising data and reporting a correlation coefficient. The 2023 exemplar shows a trendline equation of y = 0.0058ln(x) + 1.0864 with R² = 0.9907 reported alongside it, which is the level of precision the top band expects.

Interpreting and Evaluating (5 marks)

Marked on your conclusion, your discussion of reliability and validity, and your improvements and extensions.

Named in 2023, 2024 and 2025: your conclusion has to refer back to the trends you found in your analysis and to the theory in your rationale, "rather than simply restating data."

QCAA supplies its own definitions of reliability and validity, near-identically worded in the 2024 and 2025 reports: validity is the extent to which the experiment measured what was intended; reliability is the likelihood that another experimenter would obtain the same results. They have to be discussed as two separate things. A response that describes both without justifying either sits in the middle band by definition.

What separates strong from weak, from four years of reports

Forming is the criterion your school is most likely to mark higher than QCAA does. The Chemistry study guide covers how confirmation moves marks across all three IAs. For Forming specifically, the advice has stayed stable across all four reports held. Aim for a research question specific enough to answer within the length allowed, naming one independent and one dependent variable. Write a rationale that explains why those variables were chosen and links to Unit 3 subject matter such as equilibrium systems or redox. Justify modifications by their effect on reliability or validity, and build risk management into how the methodology is actually carried out, not bolted on afterward.

Analysing rewards real processing, not description of it. Naming a graph type is not the same as producing one that suits your research question, with error bars, a line of best fit and a stated correlation coefficient where relevant.

Interpreting and Evaluating rewards evidence-based reasoning, twice over. Once in the conclusion, which has to connect back to your analysis and your rationale's theory. Once in the discussion of reliability and validity, which has to stay evidence-based, not turn into a list of things that went wrong.

Common mistakes

Putting method limitations in Analysing. Limitations in this criterion are about your data. Save method critique for Interpreting and Evaluating, where it belongs and is rewarded.

Restating data in the conclusion instead of interpreting it. A conclusion that repeats a number without connecting it to the trend or the theory sits well short of justified.

Naming a modification without justifying it. "Increased the number of trials" describes an action. Stating that a single trial let random errors dominate the result, and that averaging multiple trials improves reliability, is what makes it justified.

Treating reliability and validity as one idea. They are graded together but they are different questions: reliability is about repeatability, validity is about whether you measured the right thing.

Offering only an improvement or only an extension. Both are required for the top band, and one strong suggestion of either kind will not cover for the other's absence.

A research question too broad or too narrow for the word or time limit. QCAA's repeated model research question names one independent variable, one dependent variable and the conditions held constant. If your question cannot be answered inside 2000 words or 11 minutes, it is not specific yet.

Weak versus strong wording

Before you submit

• Does your rationale explain why your two variables matter, and link them to Unit 3 subject matter?
• Does every modification say how it changes reliability or validity, not just what changed?
• Is your research question specific enough to answer inside 2000 words or 11 minutes?
• Does your data processing (graphs, error bars, uncertainty calculations) match what you are trying to show?
• Are your stated limitations about the evidence, and your method critique kept for Interpreting and Evaluating?
• Does your conclusion refer back to the trends you found and the theory in your rationale, instead of restating the data?
• Are reliability and validity discussed as two separate things?
• Does every improvement and every extension trace to something you actually found in your analysis?

If you are further along in Unit 4, the IA3 research investigation asks you to evaluate a claim using secondary evidence instead of your own experiment, which is a different skill from anything IA2 tests. The Chemistry study guide covers how all four assessments fit together and where marks are lost across the subject.