IB Diploma Assessment Explained: Papers, IAs, Extended Essay, TOK, and CAS

The International Baccalaureate Diploma Programme is one of the most recognized advanced coursework credentials in the world, offered in more than 150 countries and administered by the IBO from Geneva, Switzerland. Its assessment model is also one of the most complex. Unlike national systems that lean heavily on a single end-of-year exam, the IB distributes your final grade across externally marked papers, teacher-graded coursework, a research paper, a philosophy-style course, and a community engagement portfolio.

For students and families encountering the IB for the first time, the sheer number of components can feel overwhelming. This guide walks through every piece of the Diploma Programme assessment so you can see how they fit together, what each one measures, and where the common pitfalls lie.

The Two Main Assessment Channels

Every IB subject is assessed through a combination of two channels.

External assessment refers to the written papers that students sit during one of two global exam sessions: May (for Northern Hemisphere schools) and November (for Southern Hemisphere schools). These papers are mailed to or uploaded to IB examiners around the world, who mark them according to published mark schemes. Examiners do not know the students, and students do not know who is marking their work.

Internal assessment (IA) refers to coursework completed under teacher supervision during the two years of the programme. This can include oral commentaries, laboratory investigations, mathematical explorations, historical research papers, artistic portfolios, and similar student-driven work. Your classroom teacher marks the IA first, then a sample of student work from your school is sent to an external IB moderator who adjusts the marks if the teacher was too generous or too strict. This is how the IB keeps teacher grading calibrated across thousands of schools worldwide.

Understanding this split matters, because it means your final grade is never in the hands of a single examiner or teacher. Both channels count.

Subject-by-Subject Paper Structure

The six subject groups in the IB Diploma each have their own assessment pattern. What follows is the typical structure — individual subjects within each group may vary slightly.

Group 1 — Studies in Language and Literature

This is the student's strongest language, taught as a literature course. Assessment typically includes:

• Paper 1 — a guided analysis of two previously unseen texts. Students choose one to write about in depth.
• Paper 2 — a comparative essay drawing on two of the literary works studied in class.
• Internal assessment — an individual oral in which the student explores how a global issue is presented in two works (one originally written in the language, one in translation).

Group 2 — Language Acquisition

This is the student's second language, offered at several levels (Language B at HL and SL being the most common). Subjects include Spanish B, French B, Mandarin B, German B, and many others. Assessment typically includes:

• Paper 1 — productive skills, focused on writing in the target language for specific audiences and purposes.
• Paper 2 — receptive skills, combining reading and listening tasks.
• Internal assessment — an individual oral conducted in the target language, where the student discusses a visual stimulus and a theme from the syllabus.

Group 3 — Individuals and Societies

This group covers History, Economics, Geography, Psychology, Business Management, Global Politics, and several others. Assessment structure varies by subject, usually involving two or three papers.

• History HL has three papers, including an extended response paper on regional history.
• Economics has two papers at SL and three at HL, with the HL paper focused on quantitative analysis.
• Geography, Psychology, and Business Management follow similar two- or three-paper patterns.
• Internal assessment is typically a research investigation or analytical essay on a topic the student has chosen within the syllabus.

Group 4 — Sciences

Biology, Chemistry, Physics, Environmental Systems and Societies, and Computer Science share a similar paper structure.

• Paper 1 — multiple-choice questions covering the full syllabus.
• Paper 2 — data-based questions and extended response questions.
• Paper 3 — questions tied to the subject's option topics and practical work.
• Internal assessment — the scientific investigation, an individual inquiry where the student designs, carries out, and reports on an experiment or modeled investigation. In recent syllabus updates this has replaced the older collaborative Group 4 Project in some subjects.

Group 5 — Mathematics

Students now choose between two mathematics courses: Analysis and Approaches (more theoretical, calculus-focused) and Applications and Interpretation (more modeling and real-world, statistics-focused). Both are offered at HL and SL.

• Paper 1 — in some syllabi this is taken without a calculator.
• Paper 2 — calculator permitted, typically covering a broad range of syllabus content.
• Paper 3 — HL only, consisting of extended investigation-style problems.
• Internal assessment — the Mathematical Exploration, a student-chosen investigation of a mathematical topic presented as a written report.

Group 6 — The Arts

Visual Arts, Music, Theatre, Dance, and Film sit in Group 6 (though students may swap a Group 6 subject for an additional Group 3 or Group 4 subject). Arts assessment relies heavily on portfolios and performances rather than sit-down papers.

• Visual Arts requires a Comparative Study, a Process Portfolio documenting artistic development, and a final Exhibition of resolved artworks.
• Music, Theatre, Dance, and Film use similar combinations of performances, recordings, and written reflections.

The written paper component in this group is smaller than elsewhere, and the major project work carries most of the weighting.

Internal Assessment — Why It Matters

Across the Diploma, internal assessments typically count for 20 to 30 percent of each subject's final grade. That is enough to move a 5 to a 6, or a 6 to a 7, at the margin — and because IAs are submitted long before the final exam session, they are often the most controllable part of a student's grade.

A few things are worth understanding about IAs:

• They are student-driven. You choose your research question, the focus of your investigation, or the topic of your project within the syllabus guidelines. This is both a freedom and a responsibility — a poorly chosen question can make the rest of the IA much harder.
• Teachers mark first, IB moderates. Your teacher knows the mark scheme and applies it to your work. Then a randomly selected sample from your school is sent to an IB moderator, who either confirms the teacher's marks or adjusts them up or down. If the adjustment is significant, it applies to the entire cohort from that school.
• Deadlines sit well before the May exam session. Most schools spread IA deadlines across the second half of 11th grade and the first half of 12th grade, so that students are not trying to finish their investigations at the same time as revising for papers.

The biggest mistake students make with IAs is treating them as afterthoughts. They are not. Strong IA scores build a cushion that makes the final exams less pressured.

The Core Three

The IB Diploma has three required components that sit outside any single subject. These are sometimes called the core, and a full Diploma is not awarded without them.

Extended Essay (EE)

The Extended Essay is a 4,000-word independent research paper written in a subject of the student's choice. Students can also choose an interdisciplinary option called the World Studies EE, which explores a contemporary global issue through two subject perspectives.

Key features:

• Subject-based research. You pick a subject you have studied (or, for World Studies, two subjects) and formulate a research question within it.
• Supervisor mentorship. A teacher at your school acts as your supervisor. You meet with them across three required reflection sessions, which are recorded on a reflection form submitted with the essay.
• Graded A to E. The EE is not scored on the 1-to-7 scale used for subjects. Instead it is graded A (excellent) through E (elementary). An E is a failing condition for the Diploma.

The EE rewards topics that students genuinely care about. A narrower, well-defined question on a topic you find fascinating will almost always outperform a broad, generic question you chose because it seemed safe.

Theory of Knowledge (TOK)

Theory of Knowledge is a required course that explores how we know what we claim to know, across disciplines ranging from the natural sciences to the arts, ethics, and history. It is not a content course — there is no body of facts to memorize — but a reflective course about the nature of knowledge itself.

TOK is assessed through two pieces of work:

• TOK exhibition. Students select three real-world objects and write a commentary of up to 950 words linking each object to one of 35 internal assessment prompts (questions like "Why do we seek knowledge?"). The exhibition is internally assessed.
• TOK essay. Students write a 1,600-word essay responding to one of six prescribed titles released by the IB each session. The essay is externally assessed.

Like the EE, TOK is graded A through E.

Creativity, Activity, Service (CAS)

CAS is the experiential strand of the Diploma. Students are expected to engage in three kinds of experiences over at least 18 months:

• Creativity — arts, creative thinking, performance.
• Activity — physical exertion, sport, movement.
• Service — unpaid, voluntary engagement with a community need.

CAS is not graded on any scale. Instead, students maintain a reflective portfolio documenting their experiences, the learning outcomes they have met, and at least one CAS project (a collaborative initiative lasting at least a month). A CAS coordinator at the school signs off on completion.

The key detail many students miss: failure to complete CAS means no Diploma is awarded, even if every academic score is a 7. CAS is not optional, and it cannot be back-filled in the last month of senior year.

How the Scores Add Up

Every IB Diploma student is working toward a final score out of 45. Here is how the math works:

The three bonus points come from a matrix that combines the EE grade and the TOK grade. Two A grades across EE and TOK, for example, yield the full 3 bonus points. An E in either EE or TOK is a failing condition regardless of what the matrix would otherwise award.

Minimum for the Diploma

A student must earn at least 24 points to be awarded the Diploma, and several additional conditions must be met:

• No grade 1 in any subject.
• Grade 2 in no more than two subjects.
• Grade 3 or below in no more than three subjects.
• At least 12 points earned across HL subjects (for students taking four HLs, at least 16).
• At least 9 points earned across SL subjects.
• EE and TOK at least grade D (neither can be E).
• CAS satisfactorily completed.

These conditions are why students who technically hit 24 points can still fail to receive the Diploma. A single grade 1, or an unfinished CAS portfolio, closes the door.

HL vs SL

Students choose three or four subjects at Higher Level (HL) and the remaining two or three at Standard Level (SL), for six subjects in total.

• HL involves roughly 240 teaching hours per subject, more papers, and deeper content.
• SL involves roughly 150 teaching hours, a reduced paper structure, and slightly narrower content.
• Both are scored on the same 1-to-7 scale, and a 7 at SL is worth the same number of points as a 7 at HL.

However, universities typically care about HL choices for two reasons. First, HL subjects are the ones they weigh most heavily in admissions. Second, US and Canadian universities that grant college credit for IB scores usually do so only for HL 5 or above. An SL 7 may look great on a transcript but translate into no advanced standing at university, whereas an HL 5 in the same subject often does.

The IA Deadline Calendar

One of the underappreciated features of the IB is just how spread out the internal assessment deadlines are. Most schools organize them roughly like this:

• Second half of 11th grade. First drafts of some IAs (often the sciences and the Mathematical Exploration), early work on the Extended Essay research question, and the start of the CAS portfolio.
• Summer between 11th and 12th grade. Extended Essay writing and Group 3 research IAs often sit here, because students have uninterrupted time.
• First half of 12th grade. Final drafts of most IAs, the TOK exhibition, and the first draft of the TOK essay.
• Second half of 12th grade. TOK essay finalized, any remaining IAs submitted, final reflections on the Extended Essay, CAS portfolio closed out.
• May of 12th grade. External exam papers.

Specific dates depend on each school's calendar, but the shape is consistent everywhere: almost all of the non-exam work is submitted before the external exams begin. Students who fall behind on IAs in 11th grade pay for it in 12th grade, when they are trying to revise and finish coursework at the same time.

Closing Tips for Approaching IB Assessment

After two years of IB, most students report that the workload was manageable when they respected a few basic principles.

Start internal assessments early. IAs improve dramatically with time to revise. A first draft finished two months before the deadline is much more valuable than a polished draft finished the night before.

Choose your Extended Essay topic carefully. You will spend many months on this essay. Pick a question you actually want to answer, not one that sounds impressive. The best EE topics are narrow enough to investigate deeply and personal enough that you do not dread working on them.

Take TOK seriously. TOK is easy to dismiss as vague or unimportant. Students who do often end up scrambling on the TOK essay in 12th grade and earning grades that cost them core bonus points. Engage with the course throughout, not just at the end.

Track CAS from the first month. CAS has no grade, which makes it easy to ignore. But without the portfolio and reflections signed off by your coordinator, no Diploma is issued. Log every experience as it happens — catching up after the fact is painful.

Treat HL choices as your university signal. Universities will ask what you took at HL and what you scored. Pick subjects you can perform well in and that align with what you plan to study next.

Use the full two years. The IB is not a sprint. Students who pace themselves across 11th and 12th grade consistently outperform those who try to make up ground in the final term.

The IB Diploma assessment model is demanding precisely because it tries to measure things a single exam cannot: sustained research, independent inquiry, reflective thinking, practical skill, and community engagement. Every component exists for a reason, and every component contributes to what the final score actually represents. Understanding the structure is the first step to making it work for you.

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