After having seen Loving Annabelle, I decided to finally check out Madchen in Uniform, the film it is supposedly based on. It is easy to see why the two films are compared but the only similarities are that they are both set in a boarding school and a girl falls for her teacher. Obviously in the 1931 movie, there is a lot of longing and declaring of love but nothing actually happens and, as would become the norm for lesbians on the screen, the main character tries to kill herself at the end.
Madchen in Uniform was first released in Germany in 1931 and caused quite a stir. A re-make was done in 1958 with Romy Schneider but that film is nowhere near as dark and upsetting as the original and it almost completely removes the emotional connection between the student and the teacher. When they tried to re-release the original, it fell victim to a Hollywood code that prohibited works “possessing the flavor of sexual irregularity or perversion." Despite that, the film actually won quite a few prizes at festivals in the 30s.
The Nazis tried to ban the film and most copies were destroyed. Most of the actors were Jewish and died in the concentration camps. There is a version on YouTube with English sub-titles.
The film is a landmark in lesbian films and is probably as important to the history of queer cinema as Radclyffe Hall's book "The Well of Loneliness" was to queer literary history.