The purpose with this study was to analyse students' conception of living things, and to establish how a social constructivist learning situation affect their conceptions. The method consisted of questionnaires, followed by group discussions and a final survey. The main result was that students have everyday conceptions about scientific phenomena that are reinforced by the social interaction. Some students were positively influenced by the interaction with their peers, where non-scientific conceptions were replaced by conceptions of a scientific nature. Furthermore, the cultural artifacts are of very good means, but the study showed a strong need for a knowledgeable person, e.g.a teacher, to guide students in the right direction during the discussions. Without such guidance, misconceptions will be strengthened which might create difficulties in future learning.