Complete guide
How to write an IB Internal Assessment
The IB Internal Assessment is 20–25% of your final grade depending on the subject. This guide walks through every stage — from choosing a research question to citations — with the exact detail examiners use when marking each criterion.
Choose a focused research question
Your research question (RQ) is the foundation of your IA. It must name a specific relationship between an independent and a dependent variable. A weak RQ is 'How does temperature affect enzyme activity?' A strong one is 'How does temperature (20°C–60°C) affect the rate of catalase-catalysed decomposition of hydrogen peroxide, measured by oxygen gas volume produced per minute?' The difference: the strong version specifies the range, the exact enzyme, the substrate, and how you will measure the outcome.
Check your research question →Write your personal engagement
Criterion A (Personal Engagement) rewards authentic motivation. Examiners can tell the difference between a student who actually cares about the topic and one who picked it because it sounded easy. Write 1–2 paragraphs explaining: why this topic matters to you personally, what prior experience or curiosity led you here, and what specific choice you made in the design that reflects your own interest. Avoid generic statements like 'I am interested in biology.' Be concrete.
Build your personal engagement →Design a rigorous methodology
Your methodology needs three things: clearly identified variables (independent, dependent, and at least five controlled), a method another student could replicate exactly from your description, and enough trials or data points for statistical analysis. For science IAs, this typically means a minimum of five data points across your independent variable range, with at least three trials per data point to calculate mean and uncertainty.
Check your variables →Collect and present data correctly
Raw data tables must have column headers with units, appropriate significant figures, and a recorded uncertainty for every measurement. Processed data tables must show all calculations clearly. Graphs must have axis titles with units, a descriptive caption, plotted uncertainties (error bars), and a best-fit line or curve where appropriate. Missing any of these loses marks on Criterion D (Presentation of Data).
Check your graphs and tables →Write a criterion-specific analysis and evaluation
Analysis (Criterion E) requires you to interpret your data, not just describe it. State the trend, explain it using subject theory, and calculate a relevant statistical measure (correlation coefficient, percentage error, or uncertainty propagation). Evaluation (Criterion F) must identify the three most significant sources of error, explain how each affected your results, and propose a specific modification — not just 'use better equipment' but 'replace the 25 mL graduated cylinder (±0.5 mL) with a burette (±0.05 mL) to reduce volume uncertainty from 2% to 0.2%'.
Understand your criteria →Check your citations and references
IB IAs require a reference list for all sources consulted, even if you do not directly quote them. Every in-text citation must match an entry in your reference list. Use a consistent format (MLA, APA, or Chicago — check your subject guide). Common failures: citing a website with only the URL and no author or date, citing a secondary source as if you read the primary, and including a reference that has no in-text citation.
Check your citations →Common questions
How long is the IB Internal Assessment?
Word limits vary by subject. Most science IAs are 6–12 pages (no strict word limit but typically 2,000–4,000 words). Mathematics IAs are up to 12 pages. Language IAs are 1,500–2,000 words. Check your subject guide for the official limit.
What makes a good IB IA research question?
A strong research question names a specific independent variable, a measurable dependent variable, and the system being investigated — all in one sentence. If someone reading your RQ cannot immediately picture what you measured and what you changed, it needs refining.
Can I use AI for my IB IA?
The IBO allows AI for research support and feedback but the submitted work must be your own. Using AI to generate analysis or conclusions breaches academic integrity. iBacalao gives criterion-by-criterion feedback on your draft — the same kind of comment a teacher would make — without writing any part of the IA for you.
How is the IB IA moderated?
Your teacher marks your IA using the official rubric, then submits marks to the IBO. The IBO selects a sample of IAs from your school and re-marks them. If the IBO markers consistently give different marks than your teacher, all marks in your school are adjusted up or down by the same amount.
Tools for every stage
Research Question Helper →
Refine your RQ before you start
Variables & Controls →
Check your independent, dependent, and controlled variables
Graph & Table Checker →
Verify axis labels, units, and uncertainty
Citation Checker →
Flag bare URLs and missing reference entries
Personal Engagement Helper →
Build an authentic Criterion A section
Criterion Explainer →
Understand each criterion at each mark band