Should we only eat insect burgers in the future? Would a ban on short-haul flights within Europe make sense? Is a world without single-use plastic possible? Controversial issues surrounding climate change shape global socio-political discourse more than almost any other topic. In order to participate in the debate about climate change and its consequences, arguing is a key skill. The "Fridays for Future" movement makes it clear how relevant it is, especially for young people, to be able to actively participate in this discourse and have their say. Argumentative competencies represent an essential prerequisite for this (Domenech & Petersen 2018; Ferretti & Lewis 2013), because only those people, who are able to argue, both in terms of content and linguistically competent, can convince others. At the same time, however, written argumentation in particular, with its multiple demands (Feilke 2010), is a challenge for many writers. It is therefore not surprising that elaborated argumentative texts can only be written at the end of secondary school (Feilke 2010; Henrich 2007), while even adults sometimes still have problems with refuting counterarguments in their texts (Rezat 2014) and thus arguing controversially.

A widely used didactic approach to promote written argumentation skills is to argue orally beforehand. The effectiveness of this approach is confirmed in numerous studies from the Anglo-American area (e.g. Kuhn et al. 2016; Reznitskaya et al. 2001; Shi et al. 2019), but for German as first, second, and foreign language teaching, the evaluation of its effectiveness is so far a desideratum. Similarly, it has not yet been clarified which type of didactic interweaving of oral and written argumentation is particularly effective. These research gaps are to be addressed by the DiaLog project. For this purpose, two oral task arrangements will be designed and comparatively evaluated with respect to their practicability and their effectiveness in promoting written argumentation skills. While in one task arrangement the students continuously argue their own point of view in different oral activities (MonoDiaLog), in the other one they also argue from the perspective of opponents in the context of a role play (MultiDiaLog). MonoDiaLog and MultiDiaLog are implemented in teaching modules on nine controversial issues around climate change for DaF, DaZ and DaM classes for students aged 14-16 years and tested in high schools in three European countries (Austria, Czech Republic, Netherlands).