Schools produce success and failure. They classify adolescents into succeeding or failed subjects. It appears that school mathematics can claim an outstanding effectiveness in this regard. This stands in contrast to the efforts of mathematics educators world-wide. While there are mathematics classrooms where some students fail while their peers succeed, failure in school mathematics is as much a phenomenon that whole classes, if not whole schools, collectively experience. In the presentation, I will report on a mathematics classroom in a secondary school in a deprived area of Berlin. All students at this school share extremely low prospects concerning the outcomes of their school-career. Reporting on this classroom frequently results in reactions that disqualify the teachers as just providing bad teaching and shoots from the hip proposing easy solutions. I will argue that such a perspective operates by silencing the potentials for change that inhere in the local context. I will propose a perspective that respects the social agents as active sense makers within their contexts, even though acting senselessly from the perspective of a traditional mathematics education. Zizek's theorization of the symptom will be proposed as a tool to make sense of such a "failed teaching".