I've always had bad grades, so for that one test my mom studied very hard with me. After grades were given back, my teacher came up to me and literally said that the performance was worthy of a 2 (B) but she's given me a 4 (D) again, to motivate me.
Needless to say, motivation was not achieved.
Furthermore, it's one of the core experiences that led me to mentally check out of the school system eventually and still fuels my distrust of authorities and institutions to this day, almost 20 years later. Well done Frau Bauer.