The present thesis deals with the question, which competences up to what extent will be achieved from pupils at elementary level, when experimenting in scientific classes. In order to this, the following areas will be considered particularly, which are based on the ?model of experimental competence? by Schreiber, Theyßen, and Schecker: ?to resolve a given question?, ?to develop own questions?, ?to create an experimental design?, ?to put together devices?, ?to set up a test assembly?, ?to conduct measurements?, ?to document measurements?, ?to handle measured data?, ?to interpret measured data?, and ?to relate a result to a question?. Besides, it will be investigated, how concentrated and how systematically pupils proceed during experimenting and how much time they need for particular areas. Furthermore, it will be surveyed, whether there is a connection between the needed time for an area and the achieved competence in it or not. For the examination of these research questions, four projects of the IMST themes program ?competences in mathematical and scientific education? had been investigated. In addition, there were picture taking and audio recording of the pupils. By these data and the experiment reports, the shown competences of the pupils were established through a point system, but also the needed time and the systematic proceeding was documented.The competences of the areas ?to resolve a given question?, ?to create an experimental design?, and ?to conduct measurements? were developed strongest. According to evaluated results and on average, there was used 64 percentage of time for the ?performance?, 20 percentage for the ?evaluation?, and 16 percentage for the ?planning?. A significant and direct relation between the needed time and achieved competence had been ascertained in the sectors ?to develop an experimental design? and ?to interpret measured data?.