Theory of Knowledge (ToK) is a junior/senior, two-semester course required of all IB students. The course is depicted in the 4-year plan to be scheduled during the second semester of the junior year and first semester of the senior year. It is in one sense a course in epistemology, which is the investigation of how we know what we profess to know and how we arrive at knowledge in the various disciplines. The course investigates language as it affects perception, and it introduces students to aesthetics, logic, and ethics. ToK also serves to tie the various IB curricula together to allow students to reflect upon the knowledge they gain from science, literature, language, mathematics, and social studies.