What Are TOK and CAS in IB? How They Affect Your Score
Two of the three IB Diploma core elements. TOK contributes to your bonus points; CAS is required but doesn't add points. Here is what each demands in detail.
Velocity Tuition Academy · IB Diploma · Core Elements
Updated May 2026·Written by Velocity Tuition Academy·Reviewed by IB Diploma teachers with TOK and EE supervision experience
The IB Diploma has six subjects plus a "core" of three required components: Theory of Knowledge (TOK), the Extended Essay (EE), and Creativity, Activity, Service (CAS). TOK and EE together contribute up to 3 bonus points to the IB total via a published matrix. CAS does not contribute points but must be completed for the Diploma to be awarded.
TOK is a course about how we know what we know. Students explore knowledge questions across the disciplines — what counts as evidence in history, what makes a scientific claim "true," how arts produce knowledge that other forms cannot. It is taught across both IB Diploma years (roughly 100 hours total) and aims to develop critical thinking and reflective awareness.
The course is organised around two key questions:
How is knowledge produced?
What is the value and limits of that knowledge?
And around themes (knowledge and the knower, plus optional themes like knowledge and technology, language, politics, religion, indigenous societies) and areas of knowledge (history, the natural sciences, the human sciences, mathematics, the arts).
TOK Assessment — The Essay and the Exhibition
TOK is assessed by two pieces:
The TOK Essay (60% of TOK grade) — a 1,600-word essay on one of six prescribed titles released by the IB each year. The essay is externally marked. It is the higher-stakes piece.
The TOK Exhibition (40% of TOK grade) — students choose three real-world objects that respond to one of 35 IA prompts (e.g., "What features of knowledge have an impact on its reliability?"). Each object is commented on in around 950 words total. The exhibition is internally marked by the school and moderated by the IB.
TOK is graded on a five-letter scale: A (highest), B, C, D, E (lowest). The grade combines with the Extended Essay grade via a published matrix to award 0-3 bonus points to the IB total.
The TOK/EE Bonus Matrix
The IB-published matrix awards bonus points based on the combined TOK and EE grades:
A in TOK + A in EE → 3 bonus points
A + B or B + A → 3 bonus points
A + C, B + B, or C + A → 2 bonus points
A + D, B + C, C + B, D + A → 2 bonus points (with conditions)
B + D or C + C or D + B → 1 bonus point
C + D or D + C → 0 bonus points
D + D → 0 bonus points and a fail condition
E in either → automatic fail condition for the Diploma
The strategic implication: at minimum, aim for B or C in both TOK and EE to avoid the fail condition. Aim for A/B for 2 bonus points. Aim for A/A for the full 3.
Creativity, Activity, Service (CAS) — What It Is
CAS is the experiential learning component of the IB Diploma. Students engage in a portfolio of activities across three strands across the two IB years:
Creativity: arts, performance, creative thinking, devising and producing original work.
Activity: physical exertion contributing to a healthy lifestyle.
Service: voluntary work that benefits a community, undertaken with thoughtful reflection.
CAS Project — at least one collaborative, substantive project of one month or more that ideally combines all three strands.
There is no minimum hour count globally, though many schools impose their own guidelines (50 hours per strand was a historical guideline; the IB has formally removed the hour requirement and replaced it with quality-and-evidence-based assessment).
CAS Assessment and Completion
CAS is assessed pass/fail. There is no grade. The IB requires evidence that students have:
Engaged with all three strands (creativity, activity, service) over the two years.
Completed at least one CAS project of one month or more.
Achieved the seven CAS learning outcomes (identifying strengths and areas for growth, demonstrating challenge, planning and initiating, working collaboratively, demonstrating commitment, engaging with global significance, recognising ethical implications).
Documented their engagement in a CAS portfolio (digital or physical) with reflective entries linking activities to learning outcomes.
Students who do not satisfactorily complete CAS do not receive the Diploma, even if their subject grades and TOK/EE are strong. The CAS coordinator at the school determines satisfactory completion based on the evidence in the portfolio.
Time Investment and Strategy
Honest time guidance over the two IB Diploma years:
TOK — roughly 100 hours of class time plus 30-50 hours for the essay and exhibition. Treat the essay as a serious 4-6 week project, not a one-week scramble.
CAS — variable; most students average 2-4 hours per week across the two years on activities and reflections. The portfolio reflections are the most commonly under-prepared element.
EE — see our Extended Essay guide; roughly 40 hours of work spread over 6-9 months from planning to final draft.
The students who score the most bonus points start TOK and EE early in IB Year 1 and keep the CAS portfolio current rather than scrambling in IB Year 2.
Need TOK or EE supervision?
Our 1-on-1 IB tutors include TOK essay supervision, EE planning and writing support, and CAS reflection coaching. Most students underprepare TOK and EE — closing that gap is one of the highest-ROI investments in the IB grade.
Theory of Knowledge (TOK) is one of the three IB Diploma core elements. It is a course about how we know what we know — exploring knowledge questions across the disciplines (history, sciences, arts, mathematics, human sciences). TOK is assessed by a 1,600-word essay (60%) and an exhibition with three real-world objects (40%), graded A to E. The TOK grade combines with the Extended Essay grade for up to 3 bonus IB points.
Creativity, Activity, Service (CAS) is one of the three IB Diploma core elements. Students engage in a portfolio of activities across three strands (creativity, activity, service) plus at least one substantive CAS Project over the two IB years. CAS is assessed pass/fail — no grade. Students who do not complete CAS do not receive the Diploma.
TOK and the Extended Essay combine to award 0-3 bonus IB points via an IB-published matrix. A grade A in TOK combined with A in EE gives the maximum 3 bonus points. A/B or B/A also gives 3. B/B or A/C gives 2. Combinations involving D give 0 or trigger a fail condition. An E in either TOK or EE triggers a Diploma fail condition.
There is no formal hour requirement — the IB removed the 150-hour guideline (50 hours per strand) and replaced it with quality-and-evidence-based assessment. Schools may set their own guidelines. What matters is documented engagement in all three strands, a CAS Project of one month or more, and evidence of the seven CAS learning outcomes in a portfolio.
TOK essays demand a specific skill: writing analytically about knowledge questions, using examples from across the disciplines, with structured argument. Students used to subject-based factual writing find it unfamiliar. 1,600 words is short — every paragraph must work hard. Students who plan early and discuss prescribed titles with their TOK teacher across IB Year 1 typically perform better than those who attempt it in IB Year 2.
Yes. A grade D or E in TOK (or in the Extended Essay) combined with weak performance elsewhere can trigger a Diploma fail condition. Failure to complete CAS satisfactorily — based on the portfolio evidence — means the Diploma is not awarded regardless of subject grades. Both TOK and CAS are necessary, not optional, components.
