The courses of study consist of different modules = subjects and most modules consist of three or more different types of events:

Vorlesungen lectures hold by a professor
Vorrechenübung example exercises get calculated by an assistant of the professor
Selbstrechenübung The students calculate given exercises for themselves, while student assistants are available for questions
Fragestunde The professor or an assistant answers questions from the audience
Tutorengruppe A tutor, usually a student from a higher year, gives you a revision of the topics taught in lectures and gives you tips for the application.
Labor You will get the chance to apply your knowledge practically in a lab.
Prüfung / Klausur The inevitable final examination of the module