This presentation aims to illustrate how the integration of theory and teaching experiences can support pre-service teachers to generate knowledge for teaching mathematics. The pre-service teachers took part in a 5-week mathematics education course in a teacher education program in Sweden, in which a theory driven lesson study model entitled learning study were established to deepen the teachers’ awareness about the relationship between instruction and student learning. The course design consisted of two intervention cycles in which the pre-service teachers used variation theory as well as their teaching experiences as tools for lesson design and redesign. To enable us to identify if and how theory and experiences drawn from practice were employed and realized, we collected data from the pre-service teachers’ individual written reports at the end of the course. The unit of analysis from the written reports were 64 redesigned mathematical tasks and associated reflections about the reason for redesign. We found five different categories of how tasks were modified: expanding tasks, making tasks more explicit, making tasks less explicit, bringing metaphors and representations to the foreground, and creating new tasks. The findings could contribute to reflections and discussions about course design in teacher education and in what way the integration of theory and practice can be regarded as an important key point for pre-service teachers’ professional and sustainable learning.