IB Diploma Glossary: 40+ Terms Every Parent Needs to Know

Picture this: you are sitting in the auditorium at Zurich International School for Back-to-School Night. The IB coordinator is warm, enthusiastic, and clearly loves her job. She moves through her slides with practiced ease, dropping phrases like "TOK Exhibition," "CAS reflections," "IA moderation," and "predicted grades" as if these are self-evident concepts that every parent in the room already has pinned to their refrigerator. You nod. The parent next to you nods. Nobody asks a question. Afterwards, in the car park, you turn to your partner and say: "What was any of that?"

I have had some version of this conversation with parents in Milan, Dubai, Singapore, and Geneva more times than I can count. It is one of the most consistent experiences among families navigating the International Baccalaureate Diploma Programme for the first time — and it is completely understandable. The IB diploma terms parents need to know are genuinely numerous, genuinely specific, and genuinely consequential. This is not a curriculum where you can simply map your existing knowledge of grades and exams onto a new system and get by. The IBO, headquartered in Geneva, has spent more than fifty years building a pedagogical framework that is philosophically distinct from British A-Levels, American AP courses, or the French Baccalauréat. That distinctiveness comes with its own vocabulary, and that vocabulary is not optional.

The IB Diploma Programme explained in a single sentence: it is a rigorous, internationally standardized pre-university qualification taken over two years (typically ages 16 to 18) that combines six academic subjects with three core components and culminates in external examinations. But that sentence tells you almost nothing useful as a parent. What matters is understanding the specific language of the system — because parents who do not understand IB terminology cannot effectively advocate for their child, cannot interpret report cards, cannot have productive conversations with coordinators or teachers, and cannot make informed decisions about subject selection.

The stakes are particularly high for expat families, who are disproportionately represented in IB schools precisely because the Diploma is offered in over 3,500 schools across more than 150 countries and functions as the de facto curriculum of the globally mobile family. A family transferring from a Deutsche Schule to an IB school in Hong Kong, or from an American curriculum school in Abu Dhabi to BISS Milan, faces a double challenge: adapting to the curriculum itself AND decoding its terminology simultaneously. I recently worked with a family in Singapore who had relocated from the US system and were completely bewildered by the difference between HL and SL — they assumed it was roughly equivalent to Honors versus Regular, when in fact the distinction is considerably more nuanced and carries specific university implications.

This article is your decoder ring. I will walk you through every major term category: core components, assessment language, subject selection, and administrative processes. At each stage, I will explain not just what the term means, but why it matters for your child's grades, workload, and university prospects. By the time you finish reading, IB terminology for parents will feel considerably less like a foreign language.

The IB Diploma has three components that sit outside the six academic subjects but are non-negotiable requirements for earning the Diploma. These are Theory of Knowledge (TOK), the Extended Essay (EE), and Creativity, Activity, Service (CAS). Together they are called "the Core," and they are the source of more parent confusion — and more student stress — than almost anything else in the programme.

Theory of Knowledge (TOK)

TOK is not a subject in the traditional sense. It is an interdisciplinary course in epistemology — the philosophical study of knowledge itself — asking students to examine HOW we know what we claim to know across different disciplines. In practice, this means a student might spend a lesson questioning whether mathematical proof constitutes a different kind of knowledge than historical evidence, or examining how cultural perspective shapes scientific inquiry. For many students, especially those coming from heavily content-focused systems, this feels deeply unfamiliar at first.

Assessment has two components: the TOK Exhibition (an internal assessment where students select three objects or artefacts and connect them to one of 35 prescribed "IA prompts" issued by the IBO) and the TOK Essay (a 1,600-word externally assessed essay responding to one of six prescribed titles released each May or November session). TOK is graded on a scale from A (excellent) to E (elementary), and — critically — it is combined with the Extended Essay in the Diploma Points Matrix to generate up to 3 bonus points toward the final Diploma total. More on that matrix below. The immediate parent concern I hear most often is: "My child says TOK is pointless." I take that seriously enough to be blunt: an E grade in TOK is a failing condition for the Diploma. A student can earn straight 7s in all six subjects and still not receive the Diploma if they fail TOK. The stakes are real.

Extended Essay (EE)

The Extended Essay is a 4,000-word independent research paper on a topic of the student's choosing, supervised by a teacher at the school but marked externally by the IBO. It is, for most students, the first serious piece of academic research they undertake — a genuine mini-dissertation, complete with a focused research question, literature engagement, methodology, and structured argumentation. It is graded A through E on the same scale as TOK.

The EE does not have to be in a subject the student is currently studying, though it usually makes sense for it to be. The choice of research question is one of the highest-leverage decisions in the entire Diploma. A poorly scoped question — too broad, too descriptive, or not genuinely investigable — leads to months of frustration. I have worked with students who chose excellent questions and found the process genuinely rewarding; I have also worked with students whose first draft was essentially an essay about why a question is interesting rather than an actual answer to it. Topic selection is worth spending serious time on in Year 12 (DP1).

Creativity, Activity, Service (CAS)

CAS is not graded, but it IS a Diploma requirement — meaning failure to complete it adequately means no Diploma, regardless of exam scores. Students must demonstrate sustained engagement across three strands: Creativity (arts, creative projects, creative thinking), Activity (physical exercise and sport), and Service (community engagement with genuine learning outcomes). They must also complete at least one CAS Project — a collaborative, sustained initiative lasting a minimum of one month that integrates at least two of the three strands. CAS is documented through CAS Reflections on a portfolio platform (usually ManageBac), which I cover in detail in the Administrative Terms section.

This is the section most parents need most urgently, because it governs how their child is actually graded. The IB's assessment language is built on concepts that do not have direct equivalents in most national systems, and misunderstanding them leads to real strategic errors.

Internal Assessment (IA)

Nearly every IB subject includes an Internal Assessment component — a piece of coursework or performance assessed first by the student's own teacher and then sent to the IBO for external moderation. IAs vary enormously by subject: in Mathematics AA or AI, it is a 12-20 page independent mathematical exploration. In Physics HL, it is a self-designed experimental investigation. In English A Language and Literature, it is an Individual Oral (IO) — a recorded 15-minute discussion of a literary text and a "body of work." In History, it is a 2,200-word historical investigation built around a specific inquiry question. IA weighting typically represents 20-25% of the final grade, though in subjects like Visual Arts it is considerably higher. The critical point for parents: the IA is not homework. It is a formal, summatively graded assessment. Many students treat it casually in the early drafting stages and pay for that mistake in their final grade.

Criterion-Based Assessment

The IB does not use simple percentage marking. Instead, each assessment — IAs, the EE, TOK — is evaluated against a set of named criteria, each with its own maximum mark. The Mathematics IA, for example, is assessed against five criteria: Presentation (4 marks), Mathematical Communication (4 marks), Personal Engagement (3 marks), Reflection (3 marks), and Use of Mathematics (6 marks), totalling 20 marks. A student can demonstrate strong mathematical content but lose significant marks on Reflection or Personal Engagement — criteria that require a different kind of writing and self-awareness. Understanding the criteria before beginning an assessment is not an optional strategy; it is the only coherent strategy.

Markbands

Each criterion contains markband descriptors: detailed, public descriptions of what a piece of work in that criterion looks like at each mark level. A student reading the markband for "Reflection" in the Math IA knows exactly what an examiner expects to see for a score of 2 versus a score of 3. These documents are available in IB subject guides, which schools can access on the IBO's Programme Resource Centre. I consistently advise students to read markband descriptors before they write a single word of any formal assessment.

Moderation

Here is where things get consequential. After a teacher marks a school's IAs, the IBO selects a sample from that school and sends it to an external examiner — a moderator. If the moderator's marks align with the teacher's marks, all is well. But if the moderator finds the teacher has been systematically generous OR systematically harsh, the IBO adjusts every student's IA mark in that subject at that school — upward or downward — to correct the discrepancy. A parent in Geneva once described this to me as feeling "like the ground shifting." Her son had been told he had a solid 6 in Chemistry, and after moderation it became a 5. The school's teacher had been marking leniently, and the whole cohort was adjusted down. It is worth asking your child's school directly: have IB IA marks been moderated downward in recent sessions in the subjects your child is taking?

Grade Boundaries

Final IB grades run from 1 (minimum) to 7 (maximum) in each subject. But the raw mark thresholds that determine whether a student earns a 7, 6, 5, and so on — the grade boundaries — are set AFTER each exam session, based on the overall performance of all candidates worldwide. They shift from session to session. A parent in Zurich once asked me whether a 72% was a good score on an IB exam. My answer surprised them: it depends entirely on the subject, the session, and the paper. In a hard session of Physics HL, a 72% might be a 7. In an easier session of the same paper, it might be a 6. This is why telling your child to aim for "80% or above" is less useful than teaching them to master every criterion consistently.

Subject selection in the IB Diploma is arguably the most consequential set of decisions a student and family make, and it is saturated with terminology that shapes those decisions in ways parents are often unaware of.

Higher Level (HL) vs Standard Level (SL)

Every Diploma student takes six subjects: three at Higher Level and three at Standard Level (with the option of taking four HL and two SL, though this is demanding and should be chosen carefully). HL subjects carry more teaching hours — 240 hours over two years versus 150 hours for SL — involve greater depth of content, and have more challenging and extensive examinations. HL exams typically include an additional paper: Mathematics AA HL, for instance, has a Paper 3 focused on problem-solving that SL students do not sit.

The HL/SL choice is not simply about difficulty tolerance. It has direct university prerequisites attached. A student aiming for Engineering at Imperial College London or ETH Zurich will typically need Mathematics AA HL and Physics HL as entry requirements. Choosing those subjects at SL would effectively close the door to those programmes, regardless of the grade achieved. I recently worked with a family in Dubai who were relocating to the UK and only discovered — halfway through Year 12 — that their son's SL Physics would not meet the conditional offer requirements for his preferred Engineering programmes. The correction required significant schedule disruption. Researching university prerequisites before subject selection is not optional.

The Six Subject Groups

The IB organises its subjects into six groups, and students must select one from each (with Group 6 being flexible):

• Group 1 — Studies in Language and Literature: The student's primary language. English A, French A, Italian A, Japanese A, and so on. This is the language in which the student has the deepest literary and linguistic competence.
• Group 2 — Language Acquisition: A second language, studied at Ab Initio (beginner), B (intermediate), or A (near-native) level. Spanish B, Mandarin B, French Ab Initio, and similar.
• Group 3 — Individuals and Societies: The humanities and social sciences. History, Geography, Economics, Psychology, Business Management, Global Politics, Philosophy, and others.
• Group 4 — Sciences: Physics, Chemistry, Biology, Computer Science, Design Technology, Sports Exercise and Health Science, and Environmental Systems and Societies (ESS). Note that ESS is an interdisciplinary course that can count for either Group 3 or Group 4 but is only available at SL.
• Group 5 — Mathematics: Either Mathematics: Analysis and Approaches (AA) or Mathematics: Applications and Interpretation (AI), each available at HL or SL.
• Group 6 — The Arts: Visual Arts, Music, Theatre, Film, or Dance. Alternatively — and very commonly — students replace Group 6 with an additional subject from Groups 1 through 4.

Mathematics AA vs AI: The Most Misunderstood Choice

This is the subject selection issue I am asked about more than any other. Mathematics Analysis and Approaches (AA) emphasises algebraic manipulation, proof, and calculus — it is designed for students who enjoy abstract mathematical thinking and who are likely to pursue STEM at university. Mathematics Applications and Interpretation (AI) emphasises statistics, mathematical modelling, real-world data, and the use of graphical display calculators — it is designed for students in social sciences, business, or fields where mathematics is a practical tool rather than a discipline in itself.

The critical nuance that catches families off guard every single year: many top universities — particularly in the UK and continental Europe — require AA HL for STEM degrees and explicitly do NOT accept AI HL as equivalent, even though AI HL is technically a Higher Level qualification. UCL, Imperial, and Cambridge engineering programmes all require AA HL. Some programmes in Economics or Psychology will accept AI HL, but this varies by institution and programme. If there is any realistic chance your child will pursue a STEM-adjacent degree, the default choice should be AA. Switching from AI to AA mid-programme is painful; switching from AA to AI is manageable.

Once a student is enrolled in the Diploma and subject selections are set, a second layer of IB vocabulary becomes relevant: the administrative and reporting language that governs how progress is tracked, communicated, and ultimately converted into university offers.

CAS Reflections

CAS Reflections are the written or multimedia entries a student makes in their CAS portfolio — usually hosted on a platform called ManageBac — documenting their CAS activities. The key word is not "documenting" but "reflecting." The IBO is explicit that a log of what a student did ("I played football for two hours on Tuesday") is not a reflection. A reflection engages with the seven CAS Learning Outcomes: identifying strengths and areas for growth, demonstrating new skills, showing initiative, working collaboratively, engaging with global issues, considering the ethics of actions, and demonstrating perseverance. A strong reflection describes what happened, what was difficult, what was learned, and how that learning connects to one or more of the Learning Outcomes. Weak reflections that fail to engage with these outcomes can result in a student being deemed non-compliant with CAS requirements — which, again, is a Diploma-failing condition.

Predicted Grades

Predicted Grades (sometimes abbreviated PG) are teacher-issued estimates of the grade a student is expected to achieve in each subject at the end of the Diploma, based on performance to date. They are submitted to universities as part of the application process — and in the UK UCAS system in particular, conditional offers from universities are made based on predicted grades. A typical UK conditional offer might read: "We will offer you a place provided you achieve 38 IB points with 6,6,6 at Higher Level." If a student's predicted grades suggest they can achieve that, the offer is made. If predicted grades are lower, the offer may not materialise at all.

Predicted grades are assigned by individual subject teachers and reviewed by the IB coordinator. They are supposed to represent a genuine, evidence-based professional judgment — not an aspirational number to make a student feel good or to help them access universities they cannot realistically reach. I have seen cases where overly generous predicted grades set families up for painful disappointment when actual results came in significantly lower. I have also seen cases where a student's predicted grades were conservative and their actual results exceeded them. Neither scenario is ideal. If your child's predicted grades seem inconsistent with their performance on IAs and practice exams, it is a legitimate question to raise with the teacher.

The Diploma Points Matrix (TOK/EE Bonus Points)

The Diploma total is the sum of scores in six subjects (each graded 1 to 7, for a maximum of 42 points from subjects alone) PLUS up to 3 bonus points awarded based on the combined performance in TOK and the Extended Essay. The matrix works as follows: each of TOK and EE is graded A through E, and the combination of the two grades determines the bonus points awarded. An A in both TOK and EE earns 3 bonus points. An A and a B earn 3 points. A B and a B earn 2 points. The bonus declines as grades drop, and — critically — an E in either TOK or EE (regardless of subject grades) results in automatic failure to award the Diploma. The maximum total Diploma score is therefore 45 points (42 from subjects plus 3 bonus). The minimum passing score is 24 points, subject to several other conditions including no "failing" grades in any subject and satisfactory completion of CAS.

Other Administrative Terms Worth Knowing

• DP1 / DP2: Year 1 and Year 2 of the Diploma Programme. DP1 is typically Year 12 (ages 16-17) and DP2 is Year 13 (ages 17-18).
• May Session / November Session: The two annual exam sittings. Most schools in the Northern Hemisphere use the May Session.
• Diploma vs Certificate: A student who completes all Diploma requirements earns the full IB Diploma. A student who completes individual courses without the full Diploma requirements earns IB Course Certificates. Most universities strongly prefer the full Diploma.
• IB Coordinator: The school staff member responsible for administering the Diploma Programme — registering students, submitting work to the IBO, liaising with examiners. They are your primary point of contact for any administrative question.

For your convenience — and for those moments before a meeting with an IB coordinator when you want a fast refresher — here is a consolidated IB diploma vocabulary reference covering the terms that come up most frequently in parent conversations. This is the IB jargon explained as concisely as I can manage.

Ab Initio:

A beginner-level language course in Group 2. No prior knowledge of the language assumed. Available at SL only.

Assessment Criteria:

Named categories (A, B, C, D, etc.) against which each IB assessment task is evaluated. Students should always write to the criteria.

CAS (Creativity, Activity, Service):

The non-graded but mandatory Core component requiring sustained engagement in creative, physical, and service activities with documented reflection.

CAS Learning Outcomes:

Seven specific outcomes students must demonstrate through their CAS activities, used to structure CAS Reflections.

CAS Project:

A collaborative CAS initiative integrating at least two of the three CAS strands, lasting a minimum of one month.

CAS Reflections:

Portfolio entries documenting what a student did in CAS and — critically — what they learned, linked to the CAS Learning Outcomes.

Diploma Points Matrix:

The table that converts combined TOK and EE grades into 0-3 bonus points added to the subject total.

DP1 / DP2:

Year 1 and Year 2 of the Diploma Programme (equivalent to Year 12 and Year 13 in the UK system).

EE (Extended Essay):

A 4,000-word independently researched paper, externally marked, graded A-E. A Core requirement.

Grade Boundaries:

The raw mark thresholds that convert total exam and IA marks into a grade from 1 to 7. Set after each exam session.

Group 1–6:

The six IB subject groups. Students must select one from each group (Groups 1–5 are mandatory; Group 6 can be replaced).

HL (Higher Level):

One of three subjects taken with greater depth and more teaching hours (240 hours). Usually required by universities for specific degree programmes.

IA (Internal Assessment):

Coursework assessed first by the school teacher, then externally moderated by the IBO. Typically 20-25% of the final grade.

IB Coordinator:

The school administrator responsible for running the Diploma Programme and communicating with the IBO.

IBO (International Baccalaureate Organization):

The Geneva-based body that administers the IB programmes globally.

IO (Individual Oral):

The spoken internal assessment in Group 1 language subjects — a recorded 15-minute oral discussion.

ManageBac:

The most widely used school-based platform for managing CAS portfolios, IA submissions, and academic records in IB schools.

Markband Descriptors:

Detailed public descriptions of what a piece of work looks like at each mark level within a given criterion. Available in IB subject guides.

Math AA (Analysis and Approaches):

The algebraically rigorous, proof-based mathematics course. Required by most STEM-oriented universities at HL.

Math AI (Applications and Interpretation):

The statistics and modelling-focused mathematics course. Suitable for students in social sciences, business, or humanities directions.

May Session / November Session:

The two annual IB exam sittings.

Moderation:

The IBO process of reviewing a sample of teacher-marked IAs to verify consistency. If the moderator disagrees with the teacher, ALL marks in that cohort are adjusted.

MYP (Middle Years Programme):

The IB programme preceding the Diploma, for students roughly ages 11-16. MYP5 is the final year before the Diploma begins.

Predicted Grade (PG):

Teacher-issued grade estimate submitted as part of university applications. The foundation of UCAS conditional offers.

Prescribed Titles:

The six essay prompts released by the IBO each session from which students choose one for their TOK Essay.

SL (Standard Level):

One of three subjects taken with less depth and fewer teaching hours (150 hours) than HL.

Subject Guide:

The IBO's official document for each subject, containing the syllabus, assessment criteria, and markband descriptors. Available through the school.

TOK (Theory of Knowledge):

The Core interdisciplinary epistemology course. Assessed via the TOK Exhibition (internal) and TOK Essay (external). Graded A-E.

TOK Essay:

A 1,600-word externally assessed essay responding to one of the IBO's prescribed titles. Graded A-E.

TOK Exhibition:

An internal assessment where students curate three objects related to one of 35 prescribed IA prompts.

Total Diploma Score:

The sum of six subject grades (max 42) plus TOK/EE bonus points (max 3) = maximum 45 points. Minimum passing score is 24, subject to conditions.

If there are terms on this list that still feel unclear in context, I encourage you to bring them directly to your child's IB coordinator with the specific question: "How does this apply to my child right now?" Understanding IB language is not an academic exercise — it is the foundation of effective parenting within this system.