Teaching and learning about complex and controversial societal issues is a challenging endeavour. Students must not only gain new scientific perspectives on the issues but also be able to take ethical and philosophical perspectives in consideration. In this teaching approach, the various aims involved are complex and the teacher often ends up in problematic situations. The teacher must also deal with formal laws and regulations in addition to more informal work routines – all whilst balancing the various teaching aims. This study followed groups of teachers in an Erasmus+ partnership whereby the teachers conducted a reflexive and interdisciplinary lessons about certain complex and controversial issues, including those which are socio-scientific. Five schools in five different countries were involved (Croatia, Poland, Italy, Sweden and Turkey), and the students who participated were aged 12–16 years. With inspiration from different fields of educational research, the study aimed to induce interdisciplinary teaching about controversial issues on a structural and socio-political level at the involved schools. In addition to raising the students’ awareness of different aspects of the issues and encouraging oral discussions among the students, the lesson also highlighted the development of their ability to think critically and make decisions. The lesson was also meant to create room for the students to form their own opinions about the issues. In this study, the multi-purpose teaching method in line with these intentions is labelled “reflexive teaching”. The study aimed to explore the potential tensions that may emerge during the interdisciplinary teaching in which the schools implemented this method. From these tensions, didactical dilemmas arose in the teaching, for example, when teachers held taken-for-granted positions or did not reflect on the complexity of different motivations when making their didactical decisions. Through focus groups and participant observation in the participating countries, I began by asking about which tensions are discernible across the different classrooms. Then, I reduced the data and focused on Swedish teachers in light of the international context by asking “Which tensions are most salient for Swedish teachers?” These two questions were theoretically elevated and clustered in the discussion to become “Which didactical dilemmas may emerge during interdisciplinary teaching?” The results show a variety of emerging tensions which may cause didactical dilemmas. The tensions are anchored on different levels, concern different types of curriculum goals, relate to politics and religion as well as tensions on the classroom level. Through in-depth focus-group discussions with the Swedish teachers, four so-called meta-dilemmas emerged: 1. The student-centred classroom versus the teacher-centred classroom; 2. teaching towards educational goals versus social, democratic and character-development goals; 3. whether the teacher should be objective, neutral or take a stand (regarding the complex and controversial issues); and 4. whether adaptations for specific pupils should be made in oral discussions. The more practice-oriented purpose of the study was to contribute to pre- and in-service teacher training, and this resulted in a discussion tool. The developed tool is a didactic model which aims to raise awareness about both the potential possibilities and potential negative consequences of different positions in didactical dilemmas. By means of abductive analysis, the empirical results of the study formed the basis of a model with four quadrant matrixes. In these matrixes, different tentative positions in didactical dilemmas are illuminated by fictional teachers who present arguments about their position.