Complete guide
How to write an Internal Assessment
Written and cross-checked by IB Diploma graduates: Alexander (41), Alejandro (40), Martina (40), Victoria (38), Martin (35), Maria (34)
· Checked against official IB guidance · Editorial policy
Internal Assessment is subject-specific: the task, weighting, criteria, format and limits change across courses and assessment sessions. This guide gives a planning workflow while flagging where you must switch back to the current guide for your exact subject.
Start with the current task and criteria
Before planning sections, confirm the exact assessment task, subject guide and exam session. There is no universal IA rubric. For example, Biology, Chemistry and Physics scientific investigations from first assessment 2025 use four criteria — Research Design, Data Analysis, Conclusion and Evaluation — while Mathematics, History, Business Management and other subjects use different criteria and formats.
Choose a focused, answerable question
Your question should match the kind of inquiry your subject requires and be narrow enough to answer with the evidence you can realistically collect or analyse. In an experimental science investigation, that usually means a clearly described relationship between variables in a specific system; in other subjects, the question may instead frame an argument, inquiry or case study.
Design a method or evidence plan that fits the question
Explain how the evidence will let you answer the question. In the current sciences rubric, Research Design rewards a question in a specific context, methodological choices that collect relevant and sufficient data, control of relevant variables, safety or ethical considerations where applicable, and enough procedural detail to reproduce the investigation. Other subjects define method and evidence differently, so follow their own criteria.
Record and process evidence clearly
Use the conventions your subject expects and make the reasoning traceable. For current Biology, Chemistry and Physics investigations, Data Analysis covers clear and precise recording and processing, appropriate treatment of uncertainties, and processing that is relevant to the research question. Tables, graphs, units, significant figures and calculations should support the analysis rather than exist as decoration.
Answer the question, then evaluate the investigation
Separate what the evidence supports from what you hoped it would show. In the current sciences rubric, Conclusion must be consistent with the processed data and uncertainties and compared with accepted scientific context; Evaluation asks for specific methodological weaknesses or limitations, their relative impact, and realistic improvements that address them. Other subjects use different criterion names and expectations.
Check citations, limits and submission rules for your session
Cite sources in a consistent academic format and make every borrowed claim traceable. Then check the current guide for what counts toward the word or page limit, required supporting material, file format and any session-specific rules. Do not rely on a generic IA checklist for those details.
Common questions
How long is an IB Internal Assessment?
There is no single IA length across the Diploma Programme. The task, format and limit depend on the subject and assessment session. Biology, Chemistry and Physics scientific investigations from first assessment 2025 have a 3,000-word maximum; other subjects use different requirements. Check the current subject guide for your session.
How is an IA graded?
Internal Assessments use subject-specific assessment criteria. Teachers assess the work and the IB moderates internal assessment as part of its quality-assurance process. The exact criteria, marks and weighting depend on the subject and session.
What are the current science IA criteria?
For Biology, Chemistry and Physics scientific investigations from first assessment 2025, the four criteria are Research Design, Data Analysis, Conclusion and Evaluation, each worth 6 marks for 24 marks total. The same four criteria apply at SL and HL.
Can I use AI for my IA?
The IB does not ban AI tools. If AI-generated material is included in assessed work, it must be acknowledged and referenced; presenting AI-produced work as your own is academic misconduct. Your school may apply additional rules.
Sources & verification
Primary-source references used to verify key assessment facts on this page. Last source check: September 22, 2026.
The cross-subject workflow above is planning guidance, not a substitute for the subject guide. Current Biology, Chemistry and Physics examples refer to the scientific investigation from first assessment 2025.
- IB — Diploma Programme assessment and examsOfficial overview of criterion-related assessment and the role of internal assessment across Diploma Programme subjects.
- IB — Biology in the Diploma ProgrammeCurrent Biology curriculum and scientific-investigation assessment context, first assessment 2025.
- IB — Chemistry guide (first assessment 2025)Primary guide for the current Chemistry scientific investigation.
- IB — Physics guide (first assessment 2025)Primary guide for the current Physics scientific investigation.
- IB — Artificial intelligence in learning, teaching and assessmentCurrent IB guidance on acknowledging and referencing AI-generated material.
Tools for every stage
These tools are available in iBacalao — free to start.
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
Criterion Explainer →
Understand each criterion at each mark band
Stop reading about it
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