Chemistry

QCAA Chemistry IA3 Research Investigation Guide: Aim for 20/20

A current Chemistry IA3 guide to claim narrowing, evidence strands, scientific argument, evidence quality, conclusions and limitation-derived improvements.

By Sylligence · Published 2026-05-06 · Updated 2026-07-17 · 7 min read

A top-band Chemistry IA3 turns a broad claim into a specific chemical research question, plans complementary evidence for every part of that question, analyses trends and limitations, constructs a justified scientific argument, and then separates the research-question conclusion from cautious extrapolation back to the broader claim.

The strongest IA3 responses usually feel narrow. They do not try to solve a whole social, economic or environmental issue. They define the chemical meaning of vague claim words, such as “viable”, “effective” or “sustainable”, before selecting evidence.

What are the current Chemistry IA3 criteria?

Under the Chemistry 2025 syllabus, IA3 is a 20-mark Research investigation based on Unit 4 subject matter.

| Criterion | Marks | Top-band evidence in practice | | --- | ---: | --- | | Forming and Finding | 5 | Considered rationale, clearly developed question, sufficient relevant sources and appropriate genre/referencing | | Analysing | 5 | Sufficient relevant evidence, thorough trends and appropriate evidence limitations | | Interpreting | 5 | Justified scientific argument and conclusion, using fluent scientific language and representations | | Evaluating | 5 | Justified evidence-quality discussion, credible claim extrapolation, and considered improvements or extensions |

In this Chemistry IA series

How do you build the rationale from claim to question?

A good rationale should form a chain:

State the claim.
Identify the Chemistry concepts inside the claim.
Narrow the claim to a specific chemical relationship.
Explain why that relationship matters.
Write a research question that your evidence can answer.

If a word appears in your research question, prepare it in the rationale. For example, if a claim says a material is “viable”, decide which chemically assessable property the investigation will use: yield, degradation, energy requirement, emissions, mechanical performance or another defined measure. Do not pretend one narrow measure proves every meaning of viability.

How do you plan complementary evidence strands?

It is risky to write the perfect research question first and then discover that no useful data exists. Search for evidence early, then tighten the question around what credible sources can actually support.

Strong evidence often comes from:

peer-reviewed journal articles
university research
government or scientific agency reports
reputable science publications with transparent methods and data

For most IA3 topics, a small number of highly relevant sources is better than many weak sources. You need enough evidence to compare trends, but not so much that the analysis becomes shallow.

Map each part of the research question to evidence before drafting:

| Research-question component | Evidence needed | | --- | --- | | Independent or comparison condition | A dataset that varies or clearly distinguishes it | | Dependent chemical outcome | Direct measurement or a justified proxy | | Mechanism | Chemical model, equation or established explanation | | Context or boundary | Evidence under sufficiently comparable conditions |

Complementary strands are stronger than two graphs that repeat the same narrow point. One strand might establish a performance relationship while another tests a mechanism, limitation or condition required by the question.

How do you analyse trends rather than summarise sources?

Analysis should focus on what the evidence shows. Describe patterns with data values where possible:

Does a concentration increase or decrease the measured outcome?
Does one material produce a higher yield, lower emission or stronger response?
Is the relationship linear, curved, threshold-based or inconsistent?
Do two sources agree, or does one contradict the other?

Then use:

quantified trend -> chemical reasoning -> limitation or boundary -> implication for the research question

A graph is not analysis until you explain what the relationship means. If sources use different temperatures, compositions, units, proxies or baselines, discuss whether their results can actually be compared.

What is the difference between evidence limitations and source credibility?

Source credibility matters, but IA3 evaluation needs more than "this article is reliable". You should explain how useful the evidence is for answering your research question.

Useful limitations include:

a study tested different conditions from your chosen context
the sample size or range of values was narrow
the evidence measured a related variable, not the exact variable in your question
a model simplified the chemical system
a source supported one part of the question but not another

After identifying the limitation, explain whether it weakens, narrows or qualifies your conclusion. A narrow concentration range may mean a trend cannot be extrapolated; a proxy variable may only partially answer the question; inconsistent conditions may prevent a numerical comparison.

Source credibility is related but different. Authorship, peer review, recency, conflicts and transparent methods help judge whether a source is trustworthy. They do not replace analysis of what the actual evidence can support.

How are improvements logically derived from limitations?

Improvements make the current investigation stronger. They should directly address evidence limitations. For example, if the current evidence measures a proxy rather than the outcome in the question, find a study measuring that outcome directly. If two datasets use incompatible conditions, add comparable evidence or narrow the conclusion.

Extensions move to a related question under the broader claim. For example, if your research question evaluates one fuel emission, an extension might investigate another emission, a different fuel blend, lifecycle production data or another reaction condition. An unaddressed dimension of a broad word such as “viable” is usually an extension, not an improvement to the narrow question already answered.

Use the test in Improvements vs extensions in QCE Science assignments: does the change strengthen the same question, or create a related new one?

How do you write the conclusion and claim extrapolation?

A strong research-question conclusion:

answers the research question directly
uses the most important processed evidence
acknowledges limitations without sounding uncertain about everything
briefly retains the chemical reasoning that explains the result

Then add a separate claim judgment. State which part of the claim the credible findings support, under which conditions, and which meanings or variables remain outside the investigation. Do not claim that one narrow chemical relationship proves the entire social, environmental or commercial claim.

What does a confirmed 20/20 investigation teach us?

Sylligence reviewed a privately supplied Chemistry research investigation that the student confirmed received 20/20. It investigated whether gold nanoparticles could improve radiotherapy efficacy. No teacher-annotated ISMG was supplied, so it is calibration evidence rather than an official QCAA exemplar.

Its most transferable feature was not the topic. The rationale developed relevant concepts before deriving a measurable question; different evidence strands addressed the scientific relationship; the discussion qualified what each dataset could support; and proposed improvements followed directly from the identified evidence limitations. The conclusion answered the research question with scientific reasoning before cautiously returning to the broader claim.

Chemistry IA3 checklist

[ ] The rationale defines the chemical meaning and scope of the claim.
[ ] Every important term in the research question is prepared in the rationale.
[ ] Evidence strands collectively address every part of the question.
[ ] Trends are quantified and explained with Chemistry.
[ ] Cross-source conditions and variables are genuinely comparable.
[ ] Evidence limitations explain their effect on the research question.
[ ] Source credibility is assessed without replacing evidence analysis.
[ ] The conclusion answers the research question and retains scientific reasoning.
[ ] Claim extrapolation is separate, credible and appropriately qualified.
[ ] Improvements repair limitations; extensions investigate distinct related scope.

Frequently asked questions

Do I need exactly two studies?

No. Select sufficient relevant sources and evidence for your question. Two complementary studies may be enough in one investigation and inadequate in another.

Can a highly credible source have limited evidence?

Yes. A reputable paper may still use a narrow range, different conditions or a proxy that only partly answers your question.

Should the conclusion repeat all the analysis?

No. State the decisive evidence and briefly explain the chemical reason, then give the qualified answer. Do not introduce new evidence.

Related QCAA assignment guides

Separate evidence limitations from source credibility.
Classify improvements and extensions by question scope.
Compare primary-data work in the Chemistry IA2 student experiment guide.
Use Sylligence assignment feedback and select Chemistry IA3 Research investigation.

Sources and methodology

This guide separates current QCAA requirements from Sylligence interpretation and anonymised insight from a privately supplied, student-confirmed 20/20 response. That response is not an official QCAA sample and no private wording is reproduced.