In the winter semester 2015/16 I will be teaching two extensive courses at the University of Potsdam. Both of them are concerned with grammatical categories in German and its history. On the undergraduate level I will try to explain to what extent language change and language acquisition are related to each other. The course for graduate students, in turn, will focus on adverbial clauses. My main aim is to illustrate what kinds of adverbial clauses exist in Modern German and, in particular, how they developed.