Students’ difficulties in interpreting what counts as knowledge have been addressed in past research on science education. The implementation of progressivist pedagogy in terms of more student-active classroom practice and the introduction of a variety of discourses into the science classroom deepens students’ difficulties.The integration of different forms and demands of knowledge and discourses typified by Science-in-Context initiatives, such as within the Socioscientific framework, exemplifies this development in science education. Here, the diffuse boundaries between school subjects and other silos of knowledge leads to considerable difficulties for students to interpret what is expected from them. Such contexts having diffuse boundaries between, for example, subject discourses and other fonts of knowledge, have been describes as contexts with weak classification. The present study aims to explore students’ interpretation of what knowledge or meaning they are requested to produce in contexts with weak classification, here exemplified withinan SSI-task. We use Bernstein’s concepts of recognition rulesand classificationto analyse how 15-16 year-old students develop their discussions in groups of 4-6 students. This study reports how students’ recognitionof the educational demands enabled integration of different discourses in their discussion, and that the use of both universalistic and particularistic meanings can produce new understandings. Students who had not acquired recognition ruleswere found to keep discourses apart, expressed either as rejection of the relevance of the task, answering questions as in a traditional school task, or just exchange of personal opinions. Furthermore, they included discourses irrelevant to the issue.An important outcome of the study was that socioscientific thinking was hampered when students kept universalistic and particularistic meanings apart. This hampering results from the inhibition of dynamic exploration during SSI discussions. The results provide new insights with relevance for teachers’ guiding students towards a fruitful SSI-discourse.