Students’ difficulties in interpreting what counts as knowledge have been addressed in past educational research. As curricula have changed towards progressivist pedagogy the difficulties have deepened. The Socioscientific Issues framework exemplifies this development. It integrates different knowledges and discourses, implying diffuse boundaries between them, which in turn deepen students’ difficulties to interpret what is expected from them. Our aim is to explore students’ recognition of what meaning they are requested to produce in a context with weak boundaries between discourses. We use Bernstein’s concepts of recognition rules and classification to analyse how 15-16 year-old students develop their discussions in groups of 4-6 students. Students recognizing the educational demands integrate different discourses in their discussion and use both universalistic and particularistic meanings to produce new understandings. Students who do not understand the recognition rules keep discourses apart as in a traditional school task, answering questions or just exchanging personal opinions. And, by keeping universalistic and particularistic meanings apart the dynamics of an exploring SSI discussion is inhibited and the development of socioscientific reasoning is inhibited.