According to a constructivist understanding of learning, acquiring knowledge is always based on and directed by subjective conceptions pre-existing in the learner´s head.Against this backdrop, it is rather difficult to understand why the students´ previous ideas are paid comparatively little attention to when it comes to arranging beneficial learning situations - both in school as well as in subject-related didactical research.Following the model of didactic reconstruction this research project aims at examining 7th graders´ pre-concepts about the topic “tsunami” by employing guideline-based and problem-centered interviews which are to be interpret subsequently by means of qualitative content analysis. The study´s declared goal is to arrive at a better understanding of this topic arousing much interest on the students´ part, as it tries to reveal various patters of thought as well as difficulties in comprehension. Among others, one central observation made is that students absolutely have consolidated concepts at their command with regard to tsunami genesis, its impacts and possible preventive measures. These ideas, however, are likely to diverge blatantly from scientific concepts.