Teaching is complex. And often requested problem oriented mathematics instruction is even more complex than traditional instruction. From that special demands on the teacher and because of that on teacher education arise. At least teacher education at university should include attempts to sensitize becoming teachers for the complexity of (problem oriented) mathematics instruction first. For development and testing of new complementing elements of education, there has to be constructed a diagnostic instrument and to be elaborated more precisely, what is meant by sensitivity for complexity. First results will be given in this article.