The most effective IB Chemistry internal assessment tips are straightforward: formulate a focused research question, design a reproducible method, collect sufficient relevant data, process it accurately, and evaluate what your evidence can genuinely support. A sophisticated topic cannot compensate for weak methodology or superficial analysis.
Under the current course, first assessed in 2025, the Chemistry IA is officially called the scientific investigation. It is worth 20% of the final Chemistry grade, has a maximum report length of 3,000 words, and is assessed using four equally weighted criteria. This guide explains those criteria, a practical report structure, common pitfalls, and how exam practice strengthens the same analytical skills.
Current IB Chemistry IA requirements
The scientific investigation is an open-ended task in which you gather and analyse data to answer your own research question. The IB recommends approximately 10 hours for the investigation, although schools determine their own schedules and internal deadlines.
Both SL and HL students use the same criteria, worth 24 marks in total:
Criterion
Maximum marks
What it rewards
Research design
6
A contextualized question, justified methodological decisions, and a reproducible procedure
Data analysis
6
Clear, precise recording and appropriate processing, including uncertainties
Conclusion
6
A justified answer consistent with the analysis and accepted scientific context
Evaluation
6
Specific limitations, their effects, and realistic improvements
The current criteria do not include separate personal engagement, exploration, or communication categories. Those names belong to the previous assessment model, so older online advice can be misleading. Clear communication still matters because an examiner cannot reward scientific reasoning that is missing or ambiguous.
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The report may contain no more than 3,000 words. Charts, diagrams, data tables, equations, formulas, calculations, citations or references, the bibliography, and headers are excluded from that count. The IB does not require a cover page or contents page; instead, the beginning should state the investigation title, candidate code, relevant group candidate codes if applicable, and word count.
Students may collaborate in small groups where appropriate and may use similar methodologies, but either the independent or dependent variable must differ and each student must collect unique data. The submitted report remains individual work.
Choose a focused and workable research question
A strong question establishes a measurable relationship and enough chemical context to guide the investigation. For example:
How does temperature from 20.0 °C to 50.0 °C affect the rate constant for the reaction between sodium thiosulfate and hydrochloric acid, determined using colorimetry?
This identifies the independent variable, range, dependent quantity, chemical system, and analytical approach. By contrast, “How does temperature affect reaction rate?” is too broad to define one investigation clearly.
Choose a question for which you can obtain relevant and sufficient data with the equipment, chemicals, and time available. A familiar experiment completed precisely is usually stronger than an ambitious investigation that produces unreliable measurements. The RevisionDojo Chemistry IA ideas collection can support brainstorming, but an idea should be adapted into your own feasible question rather than copied unchanged.
Before collecting final data, run a pilot study. Use it to check that changes in the independent variable produce measurable differences, determine a sensible range, identify uncontrolled conditions, and estimate how many measurements are practical.
Build the report around the four criteria
The IB does not prescribe mandatory section headings. However, organizing the report around Research design, Data analysis, Conclusion, and Evaluation makes the evidence easy to locate. The current RevisionDojo Chemistry coursework guide provides a criterion-based planning framework.
Research design
Begin with the research question and only the background chemistry needed to justify your approach. Explain the relevant theory, expected relationship, reaction equations, and any model used in later processing. A long textbook summary wastes words unless it influences the investigation.
Your methodology should explain:
How the independent variable was changed and why that range was selected
How the dependent variable was measured or calculated
Which variables were controlled, how they were controlled, and why they matter
The quantities, concentrations, apparatus, precision, and sequence of operations
The number and distribution of measurements
Safety, ethical, and environmental considerations relevant to the actual procedure
A materials list followed by vague instructions is not reproducible. Include operational details such as equilibration time, calibration, mixing technique, endpoint definition, and the order in which readings were taken. The aim is not maximum length, but enough precision for another competent student to repeat the investigation without guessing; see RevisionDojo’s guidance on writing a reproducible IA methodology.
Data analysis
Present raw quantitative data with headings, units, consistent decimal places, and measurement uncertainties where applicable. Record useful qualitative observations separately, particularly if they help explain anomalies or limitations. Do not hide inconvenient results without a defensible scientific reason.
Processing must directly help answer the question. Depending on the investigation, this could involve means, rates, calibration curves, percentage uncertainty, propagated uncertainty, linearization, gradients, or comparison with a theoretical model. Include at least one transparent sample calculation and define equations and symbols.
Graphs should have descriptive titles, labelled axes with units, sensible scales, and suitable error bars where these are meaningful. Discuss the pattern rather than merely stating that a graph “increases.” Address gradient, curvature, intercept, scatter, anomalies, uncertainty, and whether the evidence supports the proposed relationship.
Statistical techniques should be selected because they answer a scientific question, not because they appear advanced. A regression coefficient alone does not establish causation or prove a model. Explain what each processed result means chemically and consider whether the uncertainty is large enough to weaken the apparent trend.
Conclusion
Answer the research question directly using numerical evidence from your analysis. A strong conclusion might state the direction and magnitude of the relationship, quote a gradient or calculated constant with uncertainty, and explain whether the result agrees with the predicted chemical model.
The criterion also requires comparison with accepted scientific context. This may include a literature value, established theory, a published relationship, or credible reference data. Cite the source precisely and discuss agreement or disagreement in light of uncertainty rather than declaring that your result is “close.”
Avoid claiming that a hypothesis has been proved. Experimental evidence may support a prediction within the investigated range, but limitations and uncertainty restrict how confidently the finding can be generalized.
Evaluation
Evaluation is not a list of generic human errors. Identify specific methodological weaknesses or limitations, explain their likely effect on the data or conclusion, and propose a realistic improvement that addresses the cause.
Weak statement
Stronger evaluation
Heat was lost.
Heat transfer to the cup and air reduced the measured temperature change, causing the calculated enthalpy magnitude to be underestimated.
Use better equipment.
Use a covered, insulated calorimeter with a temperature probe and extrapolate the cooling curve to the mixing time.
More trials are needed.
Repeat measurements at 40 °C because their spread was substantially larger than at other temperatures, reducing confidence in that mean.
Prioritize limitations by their effect on validity, precision, or the conclusion. Improvements should be technically possible and matched to the identified problem. An extension explores a new question; it does not replace improvement of the original method.
Common Chemistry IA mistakes
Several recurring problems prevent otherwise competent investigations from reaching the highest bands:
Choosing a descriptive task: Measuring the pH of several drinks provides comparison but may not investigate a controlled relationship.
Collecting insufficient evidence: Too narrow a range or too few useful measurements makes trends difficult to distinguish from random variation.
Treating uncertainty as decoration: Instrument uncertainties must influence processing, graph interpretation, and the strength of the conclusion.
Confusing precision with accuracy: Repeated values may be close together while all remain displaced by calibration error.
Using generic evaluations: “Human error” does not identify a mechanism, direction of effect, or improvement.
Overloading tables: Tables do not count toward the word limit, but placing explanatory prose inside them to evade the limit weakens readability.
Relying on an appendix: Essential raw data, processing, and reasoning should appear in the main report.
Following the old rubric: Separate personal engagement and communication sections are not part of the current four-criterion model.
Reviewing annotated work can make these distinctions clearer. Use Chemistry IA examples to study how evidence is communicated, but never copy wording, data, or methodology without proper acknowledgement.
How exam practice strengthens IA performance
The IA and final examinations assess overlapping scientific skills. Paper 1B includes data-based and experimental-work questions, while Paper 2 requires concise application of chemical concepts. Both reward accurate calculations, interpretation of unfamiliar evidence, appropriate significant figures, and justified conclusions.
After completing an exam question, do not simply check the final answer. Compare each step with a worked solution and ask:
Which evidence was relevant?
Why was that equation or graph selected?
Were units and significant figures handled consistently?
Did the conclusion go beyond what the data supported?
Which command term determined the required depth?
RevisionDojo’s IB Chemistry resources include per-question past-paper video walkthroughs, while the Questionbank supports targeted practice and feedback. This worked-solution review develops the same disciplined reasoning needed to explain calculations and justify interpretations in an IA.
Final checklist before submission
Before submitting, check that:
The question specifies a focused chemical relationship and context.
Every important methodological choice is explained, not merely stated.
Another student could reproduce the data collection process.
Raw and processed data are clearly distinguished.
Units, uncertainties, decimal places, and significant figures are consistent.
Calculations are accurate and relevant to the question.
The conclusion uses numerical evidence and accepted scientific context.
Each limitation is linked to an effect and a realistic improvement.
All external ideas, values, diagrams, and wording are cited consistently.
The report remains within 3,000 words and follows your school’s deadline.
You can use the RevisionDojo Chemistry IA Grader to compare a draft with the four current criteria. Treat automated or external feedback as a prompt for your own revision, not as replacement text. Jojo AI may help you understand concepts or question your reasoning, but submitted writing and analysis must remain your authentic work and any AI-produced material used must be acknowledged according to IB and school policy.
Conclusion
Scoring well in the IB Chemistry IA depends on a coherent chain of evidence: the question determines the method, the method produces relevant data, the analysis supports the conclusion, and the evaluation explains the limits of that conclusion. Precision, justification, and scientific restraint matter more than an unusually complex topic.
Use the official criteria throughout planning rather than checking them only after writing. RevisionDojo’s IA guide, examples, criterion grader, Chemistry Questionbank, and past-paper video solutions can then support a productive cycle of investigation, feedback, worked-solution review, and independent revision.
Daniel holds an MSc in Chemistry from Imperial College London and has taught IB Chemistry for over 20 years, including as Head of Chemistry. His focus is on building the conceptual understanding behind each equation rather than rote recall.
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