In this article, the argument is put forth that controversies about the scope and limits of science should be considered in Nature of Science (NOS) teaching. Reference disciplines for teaching NOS are disciplines, which reflect upon science, like philosophy of science, history of science, and sociology of science. The culture of these disciplines is characterized by controversy rather than unified textbook knowledge. There is common agreement among educators of the arts and humanities that controversies in the reference disciplines should be represented in education. To teach NOS means to adopt a reflexive perspective on science. Therefore, we suggest that controversies within and between the reference disciplines are relevant for NOS teaching and not only "the" NOS but "about" NOS should be taught, too. We address the objections that teaching about NOS is irrelevant for real life and too demanding for students. First, we argue that science-reflexive meta-discourses are relevant for students as future citizens because the discourses occur publicly in the context of sociopolitical disputes. Second, we argue that it is in fact necessary to reduce the complexity of the above-mentioned discourses and that this is indeed possible, as it has been done with other reflexive elements in science education. In analogy to the German construct "Bewertungskompetenz" (which means the competency to make informed ethical decisions in scientific contexts), we suggest "epistemic competency" as a goal for NOS teaching. In order to do so, science-reflexive controversies must be simplified and attitudes toward science must be considered. Discourse on the scientific status of potential pseudoscience may serve as an authentic and relevant context for teaching the controversial nature of reflexion on science.