The Complete IB Internal Assessment Guide

Internal Assessments (IAs) are a core component of every IB Diploma Programme subject. Unlike externally examined papers, IAs are completed during the course, supervised by your teacher, and then externally moderated by IBO examiners. They typically account for 20–25% of your final subject grade, making them one of the most controllable elements of your IB score — you have weeks or months to refine them, unlike a timed exam.

This guide explains how IAs work across different subject groups, what examiners look for when applying criteria, the most common mistakes students make, and concrete strategies for achieving top marks. Whether you are writing a History IA, a Biology lab report, or a Mathematics exploration, the principles of strong IA work are consistent.

What Is the Internal Assessment?

The Internal Assessment is a piece of coursework completed under teacher supervision that demonstrates your ability to apply subject knowledge independently. The format varies significantly by subject:

• Group 1 (Language & Literature): Individual Oral (IO) — a recorded oral commentary and discussion
• Group 2 (Language Acquisition): Individual Oral — a recorded oral assessment based on literary/non-literary works
• Group 3 (Individuals & Societies): Written investigation (History: 2,200 words; Economics: 800 words per commentary × 3; Psychology: experimental study report)
• Group 4 (Sciences): Scientific investigation report (Biology, Chemistry, Physics: 6–12 pages)
• Group 5 (Mathematics): Mathematical Exploration (12–20 pages)
• Group 6 (The Arts): Varies by subject (Visual Arts: comparative study; Music: creating/performing)

Despite these format differences, all IAs share common expectations: independent work, engagement with subject methodology, clear communication, and demonstration of understanding beyond what is covered in class.

How IAs Differ by Subject Group

Understanding the specific expectations for your subject is critical. Here is a deeper look at what distinguishes IAs across the major subject groups:

Sciences (Group 4)

Science IAs require you to design and conduct an original experiment (or simulation/modeling in some cases). The emphasis is on the scientific method: formulating a testable hypothesis, controlling variables, collecting sufficient data, processing results with appropriate statistical tools, and evaluating the methodology. Examiners want to see that you understand why you made each methodological choice, not just what you did. A common misconception is that complex experiments score higher — in reality, a simple experiment executed with rigorous methodology and thoughtful evaluation often outscores an ambitious experiment with poor controls.

History (Group 3)

The History IA is a 2,200-word investigation into a historical question. It requires you to identify and evaluate sources (Section 1), investigate the topic using evidence (Section 2), and reflect on the methods used by historians (Section 3). The key differentiator for top marks is genuine engagement with historiography — showing that you understand how different historians have interpreted the same events and why their interpretations differ based on methodology, perspective, or available evidence.

Mathematics (Group 5)

The Mathematics Exploration is unique in that it asks you to explore a mathematical topic of personal interest. There is no fixed structure, but examiners look for personal engagement with the mathematics, use of appropriate notation and terminology, and mathematical thinking that goes beyond mere calculation. The best explorations connect mathematics to a real-world context that genuinely interests the student, then demonstrate sophisticated mathematical reasoning within that context.

Economics (Group 3)

Economics requires three commentaries of 800 words each, based on published news articles. Each commentary must apply economic theory to explain a real-world event, use appropriate diagrams, and evaluate the economic implications. The challenge is demonstrating depth of analysis within a tight word limit — every sentence must contribute to the argument. Examiners penalize commentaries that merely describe the article without applying economic models.

Assessment Criteria Explained

While specific criteria vary by subject, most IAs are assessed against 4–5 criteria that evaluate similar competencies:

The most heavily weighted criterion in nearly every subject is Analysis and Evaluation. This is where the difference between a 5 and a 7 is determined. Students who merely describe their findings without interpreting them, evaluating their significance, or acknowledging limitations will consistently score in the middle bands regardless of how well they perform on other criteria.

Common Pitfalls Per Criterion

Based on published examiner reports and moderation feedback, here are the most frequent issues that cost students marks:

Research Question: Students often choose questions that are either too broad ("How does temperature affect enzyme activity?") or too narrow ("Does the pH of my school's water fountain change between 8am and 9am on Tuesdays?"). The sweet spot is a question that allows for genuine investigation within the constraints of your resources and time.

Methodology: In sciences, the most common issue is insufficient repetition (fewer than 5 trials per condition) and failure to identify and control key variables. In humanities, it is over-reliance on a single source type or failure to evaluate source reliability.

Analysis: The single biggest pitfall is describing rather than analyzing. Stating "the graph shows an upward trend" is description. Explaining why the trend occurs, whether it matches theoretical predictions, what anomalies suggest, and what the limitations of the data are — that is analysis.

Evaluation: Many students treat the evaluation section as a place to list "errors" (e.g., "human error" or "the timer was inaccurate"). Examiners want to see specific, realistic limitations that actually affected results, along with concrete suggestions for how the investigation could be improved if repeated.

How Examiners Actually Mark

Understanding the marking process helps you write for your audience. Here is how IA assessment typically works:

Your teacher marks your IA first, applying the subject-specific criteria and assigning a mark out of the maximum (typically 20–30 marks depending on the subject). Your teacher's marks are then submitted to the IBO along with a sample of student work from your school.

An external moderator (an experienced examiner appointed by the IBO) reviews the sample to check whether your teacher's marking is consistent with the global standard. If the moderator finds that your teacher has been too generous or too harsh, they adjust the marks for the entire cohort up or down. This means your final IA mark may differ from what your teacher awarded.

Key implications for students:

• Your IA must be self-explanatory — the moderator has never met you and cannot ask clarifying questions
• Clarity of communication matters enormously; if the moderator cannot follow your argument, they cannot award marks for it
• Following the prescribed structure and format for your subject makes it easier for moderators to find evidence of each criterion
• Your teacher's feedback is valuable but not final — aim to exceed the criteria rather than just meeting your teacher's expectations

Time Management for IA

Most IAs require 10–20 hours of focused work spread across several weeks or months. The biggest time management mistake is leaving the IA until the last few weeks before the deadline. This leads to rushed methodology, insufficient data collection, and superficial analysis.

A recommended timeline for a science IA (adaptable to other subjects):

• Weeks 1–2: Topic exploration, background research, research question formulation
• Weeks 3–4: Methodology design, preliminary trials, variable identification
• Weeks 5–7: Data collection (with sufficient repetitions and controlled conditions)
• Weeks 8–9: Data processing, graph creation, statistical analysis
• Weeks 10–11: Writing the report (introduction, methodology, results, analysis, evaluation, conclusion)
• Week 12: Revision, proofreading, formatting, teacher review

Starting early also gives you time to redo experiments if initial results are inconclusive, or to pivot your approach if your original methodology proves unworkable.

Editing and Revision Strategy

The difference between a good IA and an excellent one often comes down to revision. Here is a structured approach to editing your IA:

First pass: Structure and argument. Read your IA from start to finish and ask: Does every section contribute to answering the research question? Is there a logical flow from introduction to conclusion? Are there any gaps in the argument?

Second pass: Criteria alignment. Go through each criterion for your subject and highlight where in your IA you have addressed each one. If you cannot find clear evidence for a criterion, you need to add content. This is where tools like IBLens can help — by analyzing your IA against the specific criteria for your subject, you can identify which areas need strengthening before submission.

Third pass: Academic conventions. Check citations, formatting, terminology, and word/page count. Ensure all graphs have titles, axes labels, and units. Verify that your bibliography is complete and consistently formatted.

Fourth pass: Clarity and concision. Remove redundant sentences, replace vague language with specific terminology, and ensure every paragraph has a clear purpose. In subjects with tight word limits (like Economics commentaries), every word must earn its place.

For a deeper understanding of how criterion-based marking works across all IB essay types, see our IB Essay Criteria Explained guide. If you are working on your Extended Essay alongside your IA, our Extended Essay Guide covers the specific requirements for that component. For understanding how your IA mark contributes to your overall IB score, check our IB Grade Boundaries explainer.