This 1999 film focuses on life at the East-West Berlin border, specifically the teen lives of the times. As such, it has long since been used in German classrooms, though I have not used this particular film for reasons described below (I am extra picky with what I play in class!).
Besides Katharina Thalbach, who plays the mother of one of the boys, a few of the other main cast have been in some other interesting films and series, but none quite as much as Alexander Beyer, who continues to act in a variety of roles, including several more about the Cold War era. A selection of his other films are: Good bye Lenin!, Deutschland 83, Deutschland 86, and the Fifth Estate.
The sister’s chest is very briefly visible while she’s in the bath. This happens around 22 minutes in and should be simple to skip. There is a sex scene about 36 minutes in that is almost comically done and would be easy to skip. At 48 minutes in, two of the boys pee off the balcony and their genitalia is visible for a moment. This image returns in a blurry black and white view from a newspaper at 53 minutes. There is some drug use in this time that focuses on the negative effects of drugs. An hour and 14 minutes another sex scene begins, again relatively comically portrayed, but her chest is visible before and after. During the credits, there is a nude man, seen from the front.