Theory of knowledge (TOK) is assessed through an oral presentation and a 1,600 word essay. It asks students to reflect on the nature of knowledge, and on how we know what we claim to know. TOK is part of the International Baccalaureate® (IB) Diploma Programme (DP) core, and is mandatory for all students.

http://www.ibo.org/programmes/diploma-programme/curriculum/theory-of-knowledge/