The IB core: EE, TOK and CAS explained

Three compulsory elements sit at the heart of the IB Diploma — the Extended Essay, Theory of Knowledge and CAS. They're what makes the IB more than six subjects: independent research, critical reflection on knowledge itself, and learning beyond the classroom. EE and TOK together can earn up to three bonus points.

Extended Essay (EE)

The EE is an independent, roughly 4,000-word research essay in a subject of your choice, guided by a supervisor and assessed externally. You frame a focused research question, investigate it, and argue a reasoned answer. It's the closest thing the IB offers to university-style research, and it teaches you to manage a long, self-directed piece of work.

Theory of Knowledge (TOK)

TOK asks how we know what we know. It's assessed in two parts: a TOK essay on one of the prescribed titles set by the IB, and a TOK exhibition of three objects that show how knowledge appears in the real world. TOK runs through the whole diploma, sharpening the critical thinking the other subjects rely on.

Creativity, Activity, Service (CAS)

CAS is experiential learning beyond academics — creative pursuits, physical activity, and service to others, plus a CAS project. It isn't graded, but it is required: you document experiences and reflections against a set of learning outcomes. It's where the IB's 'whole person' philosophy lives.

How the core affects your diploma

EE and TOK are graded and combine for up to three bonus points on top of your subject scores — points that can lift a 42 to a 45, or rescue a borderline diploma. CAS must be completed satisfactorily to be awarded the diploma at all. Treat the core as load-bearing, not an afterthought.