The aim of this study is to provide theoretical and practical knowledge about strategies and techniques for training primary school education pre-service teachers (PSTs) for Pedagogical Improvisation (PI). Data was collected during two iterations of cross-disciplinary art/science school interventions in Norwegian 3rd-grade classes, which provided a framework for a process based on Educational Design Research theory. Data included interviews with PSTs (n = 11), and their reflection notes, following their participation as practicum educators in the interventions as well as in separate PI rehearsal sessions in a controlled classroom environment. PSTs' experiences and perceptions were coded and analysed, leading to the development of a theoretical model on which future trainings for classroom improvisation may be based. Implications for improvisation as an integral part of teacher education, its professionalization, and areas for further research are described as conclusions.