How to Improve Your QCE Chemistry Internal Assessment Results: 2025 Subject Report Breakdown

In QCE Chemistry, your three internal assessments (the data test, the student experiment and the research investigation) make up 50% of your final result. In 2025, Chemistry's student experiment had the lowest agreement between school and QCAA marks of any QCE assessment in our 2025 subject report series, so understanding what markers expect really matters.

This guide breaks down the internal assessment sections of QCAA's 2025 Chemistry subject report. It covers how students scored on each IA, what strong responses did, and the changes under the revised 2025 syllabus that students completing Units 3 and 4 from 2026 need to know. For the external exam, see our companion 2025 QCE Chemistry external assessment breakdown.

Key Takeaways

• Internal assessments are worth 50% of your Chemistry result: data test (IA1) 10%, student experiment (IA2) 20%, research investigation (IA3) 20%.
• QCAA agreed with schools' student experiment marks only 78.28% of the time, and almost every change was downwards. Research and planning was lowered in 15.79% of samples.
• Research investigation marks agreed 83.77% of the time, again with changes mostly downwards.
• Strong experiments analysed uncertainty in the data (percentage uncertainty, percentage error, error bars, R²), not just problems with the method.
• Strong research investigations reached a conclusion about the research question, not the claim, and evaluated the limitations of the evidence, not just the credibility of sources.

How Internal Assessment Works in QCE Chemistry

Your school writes each IA, but before students sit it the QCAA must endorse it, checking that it matches the syllabus and is fair. After marking, the QCAA confirms a sample of student responses to check that your school's marks are accurate.

💡 New to the system? Read our explainer on how QCE internal assessments work.

How Students Scored in 2025

Approximate values read from the mark distribution charts in QCAA's 2025 Chemistry subject report.

Full marks was the most common result on every IA, and most students finished in the 40s out of 50. Because results are so high, small slips in the experiment or research investigation can make a noticeable difference.

How Reliable Were School Marks?

Source: QCAA Chemistry subject report, 2025 cohort.

What this means for students:

• Your data test mark will stand. QCAA agreed with every school's IA1 marks.
• More than 1 in 5 schools' student experiment marks were changed, almost always downwards. The criteria lowered most often were Research and planning (15.79%), Interpretation and evaluation (11.24%) and Analysis of evidence (11.00%).
• Research investigation marks were lowered most often in Conclusion and evaluation (9.07%) and Research and planning (8.35%).
• Only 47% of school research investigation tasks were endorsed first time, mostly because the claims did not align with Unit 4 subject matter.

IA1: Data Test (10%)

The data test gives you datasets and short-response questions under supervised conditions.

What QCAA's Report Shows

• Use the data, not just theory. QCAA praised questions that asked students to use evidence from the dataset, for example "Deduce the position of the equilibrium using data to support reasoning", rather than explaining Le Châtelier's principle from memory.
• Justify with specific evidence. A full-mark sample classified an acid as weak using features of its titration curve, such as the initial pH, the buffer region and the shape of the vertical section at equivalence.
• Show your working. A typical "Calculate Kc. Show your working" question gives 1 mark for the value and 1 mark for the working.
• Cut-offs are applied exactly. 6/10 is 60%, which is not greater than 60%, so it earns 6, not 7.

What Changes for IA1 Under the 2025 Syllabus

• Perusal time is 5 minutes.
• The question specifications have been revised. For example, compare now aligns more closely with analysing data (similarities and differences).

IA2: Student Experiment (20%)

The student experiment asks you to modify a practical, collect primary data, analyse it and write a scientific report that answers your research question.

How Students Scored on Each Criterion

Approximate values read from QCAA's 2025 criterion charts.

What Earned the Marks

Research and planning: QCAA wants a specific research question that leads directly to a conclusion. Its example: "What is the relationship between the cell potential and the electrolyte concentration in a Daniell cell at 25 °C when one electrolyte concentration varies and the other is constant at 1 M?"

The rationale must explain why the variables were chosen and link them to Unit 3 concepts, and every modification must be justified. QCAA's samples included:

• an electrolysis experiment that switched to copper electrodes, measured mass loss at the anode (so deposits weren't wiped off when drying the cathode), and increased concentration and run time to reduce percentage uncertainty
• a galvanic cell experiment that tested five concentrations (0.2–1.0 M), increased trials from 1 to 3, used a digital multimeter (±0.01 V instead of ±0.1 V) and always read the voltage 5 seconds after connecting.

Finding: Your method must collect data that measures variables (such as pH, concentration, temperature or time) rather than just comparing products, and enough of it to identify trends and uncertainty, for example cell potential at five concentrations.

Analysis of evidence: Strong responses processed their data with:

• mean values, absolute and percentage uncertainties and percentage error
• scatter graphs with lines of best fit, error bars, gradients and R² values.

Limitations had to come from the data itself (precision, reliability and random error), not just general problems with the method.

Interpretation and evaluation: Strong conclusions referred to the trends found in the analysis and compared them with the theory in the rationale. In the electrolysis sample, the student found a linear increase in mass loss from 0.02 g (±100%) at 2 V to 0.07 g (±34%) at 10 V, then explained two opposing errors: impurities falling from the anode (raising mass loss) and oxygen evolution at higher voltages (lowering it). Validity and reliability discussions had to refer to data, systematic and random errors and accepted values. Extensions had to follow logically from the limitations of the data.

What Changes for IA2 Under the 2025 Syllabus

• The task specification language now matches the mid-level descriptors in the marking guide.
• The criteria are organised differently, but the standards teachers apply remain the same.

IA3: Research Investigation (20%)

The research investigation asks you to evaluate a claim about Unit 4 chemistry (the properties and structure of organic materials, or chemical synthesis and design) using secondary evidence.

How Students Scored on Each Criterion

Approximate values read from QCAA's 2025 criterion charts.

What Earned the Marks

Research and planning: Strong rationales showed how a broad claim was narrowed into a specific, chemistry-focused research question. QCAA's samples:

• "Bioplastics are better than conventional plastics" became a comparison of the tensile strength and biodegradability of PLA and LDPE, explained through their structures (ester links in PLA can be hydrolysed, while LDPE's non-polar −CH₂− chains resist degradation).
• "The chemical structure of pesticides results in undesirable properties" became a comparison of the stability and persistence of DDT and malathion. The student explained why the first research question was too broad before refining it.

QCAA's own example of a specific research question: "Does the improved synthesis from ibuprofen's original route to its new green route result in less waste reactants and more useful products?"

Analysis and interpretation: Strong responses used the chemistry of the molecules to explain the evidence. For example, PLA's semi-crystalline structure and hydrogen bonding explained its higher tensile strength compared with branched LDPE. They also explained how each limitation weakened the evidence, such as relying on a review article that combined experiments with different methods.

Conclusion and evaluation: QCAA said strong responses:

• answered the research question, not the claim
• discussed the quality of the evidence in terms of its limitations, not just the credibility of the sources
• suggested improvements that would give more valid or reliable evidence
• suggested extensions covering parts of the claim the research question did not address
• extrapolated carefully. One sample noted its biofuel findings only covered biodiesel from one algae species, so further work was needed before fully supporting the claim.

What Changes for IA3 Under the 2025 Syllabus

• The qualifiers describing each task specification have been revised.
• The syllabus now gives examples of credible sources students can use.
• Group elements have been added to some Forming and Finding activities.

💡 Get a clear picture of every cognitive verb with our complete guide to QCE cognitive verbs.

How to Improve Your Chemistry IA Results

• In the data test, use evidence from the data to justify every answer.
• Write a specific research question that names the variables and conditions.
• Justify every modification by explaining how it improves reliability or validity.
• Collect enough data, such as five values of the independent variable with repeat trials.
• Quantify uncertainty with percentage uncertainty, percentage error, error bars and R².
• Base limitations on your data, then link improvements and extensions back to them.
• In the research investigation, explain the evidence with chemistry, such as structure, bonding and functional groups.
• Answer the research question first, then carefully extend your findings to the claim.

For more preparation:

• read our 2025 QCE Chemistry external assessment breakdown
• follow our guide to getting an A in QCE Chemistry
• see our 2025 QCE Biology internal assessment breakdown
• learn how IA1, IA2 and IA3 work.

Need Help With QCE Chemistry?

Our QCE Chemistry tutors work one-on-one with students to prepare for the data test, design and analyse a high-scoring student experiment, and write a well-evaluated research investigation.

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Source: Queensland Curriculum & Assessment Authority, Chemistry subject report, 2025 cohort (January 2026).