Teleology has been described as an intuitive cognitive bias and as a major type of student conception. There is controversy regarding whether teleological explanations are a central obstacle to, are legitimate in, or are even supportive of science learning. However, interaction in science classrooms has not yet been investigated with regard to teleology. Consequently, this study addresses the question of how teleological explanations emerge in science classroom interactions about evolution and how teachers and students address emerging teleology. In this article, we introduce a theoretical and methodological framework drawing from the sociology of knowledge and systems theory, suggesting that this framework may enrich the understanding of knowledge construction and of social practices in the science classroom because it enables distinguishing between explicit and tacit knowledge. We investigated seven secondary school units about evolution and present data from four grade-12 classes in Germany, a country with very few creationists, to contrast two ways in which teleology is addressed. In the first type, the teachers combine intentional and need-based teleological explanations with aspects of scientific theories in an ambiguous way. Contrastingly, in the second type, the teachers construct a duality between correct mechanistic and incorrect teleological explanations by discrediting preceding scientific theories. In the discussion, we argue that the presented sociological approach can also be valuable in other science education contexts, such as creationism, the nature of science and socio-scientific issues, because classroom interaction involves tacit communication, such as a tacit epistemology, which are essential grounds for the students' knowledge construction.