In the course of PISA and TIMSS a lot of out-of-school lab days have been established; as non-formal extracurricular learning environments they shall provide an efficient addition to formal learning at school. The "ELKE" project is a non-formal extracurricular learning lab that aims at linking curricular content and competence-centred activities. This makes it an effective addition to chemistry education at school. Additionally, "ELKE" is a teaching/learning-environment for university teacher training. The poster illustrates the general concept as well as the contextual design of "CSI Vienna", the Viennese experimentation day. Furthermore, it shows first results concerning the effectiveness of the "ELKE" student lab on learning. These results will also be related to the outcomes of studies on "ELKE" as a teaching/learning-environment for future chemistry teachers. [This paper was published in: "Research on Outdoor STEM Education in the digiTal Age. Proceedings of the ROSETA Online Conference in June 2020," edited by M. Ludwig, et al., WTM, 2020, pp. 205-208.]