One of the strategies linking abstract topics such as climate change or sustainable mobility with everyday action is to implement temporary urban interventions. They are regarded as part of participatory planning processes that help to network different urban participants and discuss solutions for the development of urban qualities at eye level. Urban interventions are experiments, they initiate open debates instead of complex and tedious planning processes. The understanding of the city as a laboratory at the interface of science and practice is portrayed in a seminar at the at the University of Duisburg-Essen in 2014. It demonstrated how street space could be designed and used alternatively. In a specific district, different concepts for urban interventions in public space were developed and put into practice for one day. On the one hand, the experiments showed that municipalities and other stakeholders need more courage for experiments in order to offer residents new means to express their desires for change. On the other hand, temporary urban interventions provide new options for public institutions and planning professionals to break free from perfected and fossilized planning routines. How interventions can be integrated in German urban planning practice is presented in the end of this article.