IB Internal Assessment: Criteria, Weightings, and Complete Workflow
The IB Internal Assessment (IA) accounts for between 20% and 25% of the final grade, depending on the subject and level. It is graded by the student’s own school teacher using the official IBO criteria, and then externally moderated by the IBO to ensure that the standard is consistent across all IB schools worldwide. In the sciences (Biology, Chemistry, Physics), there are four criteria, each worth 6 points out of a total of 24. In ESS, there are six criteria worth 30 points. In Mathematics (AA and AI), there are five criteria worth 20 points.
It is neither an optional assignment nor a secondary component: AI is part of the IB’s official assessment model, and its results are incorporated into the numerical score that universities receive. Understanding how it works—what is assessed, who assesses it, and within what timeframes—is essential for any student who wants to maximize their final score.
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What is the IB Internal Assessment, and who grades it?
Internal Assessment is the coursework component of the Diploma Program. It is called “internal” precisely because it is marked in the first instance by the student’s own school teacher—not by an external IBO examiner, as is the case with final exams. The teacher applies the official criteria published by the organization and assigns a provisional grade to each student.
Once all the school’s grades have been collected, the IBO selects a sample of assignments and sends them to an external moderator. That moderator compares the teacher’s grading to the global standard and, if a systematic deviation is detected, applies an adjustment to all the school’s grades in that subject. The final grade is determined by the IBO following this process, not by the teacher.
(Source: IBO Assessment Principles and Practices — A Guide to Assessment for Teachers and Coordinators, ibo.org.)
How much does AI factor into the final IB grade?
The IA accounts for 20% of the final grade in Biology, Chemistry, Physics, ESS HL, Math AA, and Math AI (all levels). The exception is ESS at Standard Level, where the IA accounts for 25% —the highest weighting among all IB science subjects.
| Course | Level | Maximum IA Score | Weight in the final grade |
|---|---|---|---|
| Biology | HL and SL | 24 points | 20% |
| Chemistry | HL and SL | 24 points | 20% |
| Physics | HL and SL | 24 points | 20% |
| ESS | SL | 30 points | 25% |
| ESS | HL | 30 points | 20% |
| Math AA | HL and SL | 20 points | 20% |
| Math AI | HL and SL | 20 points | 20% |
Source: Official IBO Subject Briefs — Biology, Chemistry, Physics (first assessment 2025); ESS (first assessment 2026); Mathematics AA and AI (first assessment 2021). Available at ibo.org.
That 20–25% can be the difference between a 5 and a 6, or between a 6 and a 7. If you want to understand how IB grades are calculated in detail, check out our guide to IB grades. Unlike the final exam—where the result depends on a single day—the IA is a planned opportunity, involving weeks of work, during which students can prepare and receive guidance from their teacher.
What is the format of the IA in the sciences (Biology, Chemistry, and Physics)?
In IB Chemistry, IB Physics, and IB Biology, the IA is called Scientific Investigation. Students formulate their own research question, design and conduct the experiment, collect data, analyze it, and draw conclusions. The written report is limited to 3,000 words.
The four assessment criteria in the curriculum effective in 2025, along with their maximum scores:
- Research Design (max. 6 points): Is the research question well-formulated, and is the methodological design appropriate and reproducible?
- Data Analysis (max. 6 points): Are the data processed and interpreted correctly?
- Conclusion (max. 6 points): Are the conclusions supported by the data and connected to the broader scientific context?
- Evaluation (max. 6 points): Does the student rigorously evaluate the limitations of the method and propose realistic improvements?
The criteria are identical for HL and SL. What varies is the context of the syllabus within which the research is framed: an HL student has access to additional content that can broaden the scope of the question.
What is the format of the Individual Investigation (II) in ESS?
In ESS, the IA is called Individual Investigation and has a maximum length of 3,000 words, just like in the other science courses. The difference is that ESS is an interdisciplinary subject—it combines scientific methodologies with social and ethical perspectives—and its assessment criteria reflect that nature.
The six assessment criteria for the new ESS curriculum (first assessment in 2026), along with their maximum scores:
- Criterion A — Research Question and Inquiry (max. 4 points): Does the student identify a relevant environmental problem and formulate a specific and original research question?
- Criterion B — Strategy (max. 4 points): Is the research approach appropriate for answering the question?
- Criterion C — Method (max. 4 points): Is the data collection method appropriate and reproducible?
- Criterion D — Treatment of data (max. 6 points): Are the data processed and presented correctly?
- Criterion E — Analysis and Conclusion (max. 6 points): Is the analysis rigorous, and are the conclusions supported by the data?
- Criterion F — Evaluation (max. 6 points): Does the student thoroughly evaluate the limitations of the method and the implications of the results?
Total: 30 points. The criteria are the same for SL and HL.
What is the format of the Independent Assignment in Math (Math AA and Math AI)?
In IB Math, the IA is called Mathematical Exploration. Students choose an area that interests them and write a research paper exploring a specific aspect with rigor and depth. The paper is between 12 and 20 pages long and is graded on a scale of 20—the same format applies to both AA and AI, as well as to SL and HL.
The five assessment criteria in effect through May 2028, inclusive:
- Presentation (max. 4 points): Is the paper coherent, well-organized, and concise?
- Mathematical Communication (max. 4 points): Does the student use mathematical notation, symbols, and representations correctly and consistently?
- Personal Engagement (max. 3 points): Does the student explore the topic in a genuinely personal and creative way, going beyond simply reproducing textbook mathematics?
- Reflection (max. 3 points): Does the student review, analyze, and evaluate their own work throughout the exploration?
- Use of Mathematics (max. 6 points): Is the mathematics used relevant, correct, and appropriate for the course level?
The criterion that distinguishes HL from SL is “Use of Mathematics”: in HL, sophistication and rigor are required, with explicit justification of the steps. In SL, the requirement is correctness and relevance, without that additional level of sophistication.
Note: The IBO has announced a revision of the Mathematics assessment criteria, effective with the first assessment in May 2029. The current criteria apply in full to any student taking the exam through 2028.
(Source: IBO Mathematics AA and AI Guides, first assessment 2021, pp. 20–30, ibo.org.)
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When does the AI begin, and how long does it actually take?
The IBO officially allocates 10 hours of instructional time to Scientific Investigation in science and Mathematical Exploration in mathematics. These are the hours the IBO recommends dedicating to the investigation phase within the school setting—not the actual total time students spend on the task. In practice, the actual time spent—including independent work outside the classroom, iterations, writing, and revisions—far exceeds that figure.
The process begins in the first year of the Diploma (DP1) and continues through the second year (DP2). The following timeline is for guidance only; specific dates are set by each school:
| Stage | Approximate time | What Happens |
|---|---|---|
| Topic Selection | DP1, Semesters 1–2 | The student proposes a research question, and the professor approves (or rejects) it |
| Development | DP1, Quarter 3 — DP2, Quarter 1 | Design, data collection, analysis, report writing |
| Draft Review | DP2, Q1 | The professor reviews a single draft and provides oral or written feedback |
| Submit to the professor | DP2, Q1-Q2 | The student submits the final version; the instructor grades it according to the official criteria |
| Submission to the IBO | DP2, Q2 (before May) | The coordinator uploads the sample and the grades to the IBO platform |
| External moderation | April–June | The IBO adjusts scores if it detects a deviation from the global standard |
| Publication of Results | July | Final grades are published, now incorporating the AI with the moderation adjustment |
What happens if the professor rejects the AI topic?
The teacher may reject a topic for academic reasons—such as a question that cannot be researched, an inappropriate scope, or irrelevance to the syllabus—or for practical reasons: lack of equipment, safety risks, or inaccessible data. The authority to approve lies with the school, not the IBO. There is no appeal to the IBO at this stage; the appropriate course of action is internal dialogue with the IB coordinator if necessary.
How is the DP2 research project developed and submitted?
The IBO allows the teacher to provide general guidance and to review a single draft with oral or written feedback—without being able to correct it or suggest specific changes. The next version submitted by the student is the final one.
Each school sets its own internal submission deadline, always weeks or months before the IBO submission window closes. The school’s schedule takes precedence.
What happens if there isn’t enough data to support the hypothesis?
Failing to confirm the hypothesis does not necessarily result in a low grade. The IBO’s criteria do not reward results that are as expected; rather, they reward rigor in analysis and honesty in evaluation. A result that contradicts the hypothesis—if thoroughly analyzed in the “Evaluation” section—may score as well as or better than one that confirms it without analytical depth. What the IBO penalizes is drawing conclusions that the data do not support, or a flawed experimental design. If the data are insufficient for reasons beyond the student’s control, the Evaluation section is the place to explain this in detail.
Can the IBO change the grade given by the teacher?
Yes, and this is one of the most important aspects that students and families need to understand. The moderation process can adjust scores up or down. If the IBO determines that the teacher has graded consistently more generously than the global standard, the school’s scores are lowered; if the teacher has graded consistently more strictly, they are raised.
The adjustment applies to all students at the school in that subject, not just those in the sample. According to the IBO Assessment Guide for Teachers and Coordinators (ibo.org): “If the teacher is consistently under- or over-marking, this adjustment will be the same for each of the teacher’s candidates. If the teacher is under- or over-marking either at the top or bottom of the grade range, the adjustment may vary across the range.”
The grade that the teacher gives the student during the course is, therefore, provisional. The final grade is determined by the IBO after moderation and is published in July.
What about academic integrity and the use of generative artificial intelligence?
The IBO requires that the work be original and that the teacher certify it before submission. The use of generative AI tools to produce any part of the work is subject to the same academic integrity policies as plagiarism. Starting with the May 2025 sitting, the IBO has strengthened its authenticity verification procedures. The consequences of a violation may include the annulment of the subject grade or the entire Diploma. If you have any questions, it is best to consult with your school’s IB coordinator before you begin writing.
Can you request a review if the AI score drops after moderation?
Yes. The student or school may request a Category 3 Enquiry upon Results (EUR): a re-moderation of the school’s AI sample. There is a fee for the request, which is refunded if the grade changes as a result of the review. The deadline is after the release of results in July, and the process is managed by the school’s IB coordinator.
How can EPIC Prep help with the IB Internal Assessment?
AI is the area where prior preparation makes the biggest difference. Knowing the criteria before choosing a topic—not after starting the research—radically changes the outcome.
At EPIC, we support students whether they’re already in a tutoring program with us or are seeking specific support solely for the AI section. Depending on each student’s needs, we conduct a personalized assessment of the workload and design a tailored support plan. We can provide support in three distinct phases:
Phase 1 — Brainstorming and topic identification. We guide students in developing their own ideas through structured work sessions. Many students get stuck at this stage; our goal is for the student to come up with their own idea—we never impose one on them—using a methodology that streamlines the process.
Phase 2 — Development through the first draft. Once the topic has been approved, we guide the student through the research design, data collection, and structuring of the report, providing explicit instruction on what the IBO values for each criterion. The work is always the student’s own; we provide the framework and guidance so that they know exactly what they are doing and why.
Phase 3 — Final Review. We review the student’s draft against the IBO’s assessment criteria and identify areas for improvement before the final submission.
Some students work through all three phases with us, while others only need support with one or two. If your child is starting DP1 and hasn’t chosen a topic yet, or is in DP2 and needs help structuring the report, please feel free to contact us.
Frequently Asked Questions About the IB Internal Assessment
Is the IA topic approved by the IBO or the school teacher?
The IBO does not approve individual topics. Approval is the sole responsibility of the teacher, who acts as the first line of review. There is no appeal to the IBO at this stage.
How many words must the AI be?
In Biology, Chemistry, Physics, and ESS, the maximum is 3,000 words, according to the current subject guides. In Mathematics (AA and AI), the exploration is between 12 and 20 pages.
Does an unconfirmed hypothesis result in a lower score on the IA?
No. The IBO criteria evaluate the rigor of the design, analysis, and evaluation—not whether the result matches the hypothesis. An unexpected result, if well analyzed, can score as high as—or even higher than—one that confirms the hypothesis without depth. What is penalized is drawing conclusions that the data do not support.
How is the AI score combined with the final exam score?
They are not added directly; they are scaled. The IBO applies a scaling factor to each component so that its weight corresponds to the official percentage. In Biology SL, for example, the IA has a maximum score of 24 points and a weight of 20%, so the scores are scaled by a factor of 20/24. The resulting total score determines the final grade for the subject (on a scale of 1 to 7) according to the IBO’s grade boundaries for that sitting. (Source: IBO Assessment Guide for Teachers and Coordinators, ibo.org.)
Is the weighting for the IA the same in HL and SL?
In Biology, Chemistry, and Physics, the weighting is identical at both levels (20%). In ESS, it varies: 25% at SL and 20% at HL. In Mathematics, it is 20% at all levels, although the “Use of Mathematics” criterion requires greater sophistication at HL.
Can the AI score be reused for a retake?
Yes. During a retake, the AI score from the original session is automatically carried over to the new session: the student only retakes the written exams. However, if the student wants to submit a new AI—because the original score was low or they wish to improve it—they may do so. In that case, the work must be entirely new, the school administering the retake must be willing to supervise it (something not all schools agree to, especially if the student no longer attends there), and the new grade replaces the previous one with no guarantee of improvement. In addition, an additional moderation fee applies. If there have been changes to the curriculum since the original exam session, the student may be required to follow the new requirements. The definitive source is the IB coordinator and the official documentation on ibo.org.
For more information about the IB assessment system, visit the official “Assessment” section on ibo.org.
We hope this article has answered your questions. If you have any questions about your preparation, please contact us and we will be happy to explain how EPIC Prep can help you achieve your goals.
