According to the constructive pedagogical trends, the formation of misconceptions significantly inhibits conceptual changes, thus resisting teaching and learning processes. The present research examines the knowledge of teacher training students from the point of view of natural sciences and pedagogy. We assume that the formation of natural science misconceptions is often facilitated by teachers who themselves have their own misconceptions regarding these notions. Our target group includes Hungarian university students from Romania who will be teaching natural science concepts during their teaching career (students of biology, physics, as well as preschool and primary teacher training students enrolled in the academic year 2018/2019). We intend to explore and investigate the natural science misconceptions and their peculiarities among students. The survey is based on a traditional paper-based questionnaire, in which we ask for conceptual maps, while we also ask specific definition-centered questions about natural science concepts, as well as open questions based on reasoning. Participants wrote many terms for the key concepts, with 262 students totalling 6874 terms, an average of 1145 terms per key term. The results of the open-ended questions and the conceptual maps suggest that there is a significant number of participants who are unfamiliar with the key concepts of natural science.