The education of teachers in mathematics consists of two parts: enhancing the math-skills of the students and education in didactics. Mainly the math is taught in lessons for 50 to 100 students or even more. This has wrong influence to the teaching style and the attitude towards mathematics. This paper reports about a project, where active schoolteachers are involved in teaching the mathematics content. This is done in workshops, where the teaching can be a model for teaching a class. In addition there is the chance to inspire the students for mathematics.