Cambridge consists of a central university and 31 independent colleges. The colleges and the university collaborate in teaching undergraduates: the university provides lectures and laboratory space and colleges provide "supervisions". During a typical one-hour supervision, a supervisor provides small-group instruction to two or three—and at most five—students.

During a supervision, students get personalised instruction on any issues that they might have been confused about in class. They also get coverage of exam questions from past exams and feedback on any homework questions that they had been set by the supervisor. This allows for a customised educational experience for each student. Supervisors can be professors, graduate students, or former students who work in the Cambridge area.