This book is dedicated to Konrad Krainer. Numerous current developments in the Austrian education system owe crucial impulses to his contributions: the establishment of subject didactics in Austria, new initiatives in teacher education, and the networking of school practice, pedagogical universities, and universities. Almost twenty years ago, he initiated the IMST project, one of the most important school innovations, especially in the fields of mathematics and natural sciences. To this day, he remains a central source of inspiration and recognized early on that effective reforms must be approached holistically: direct engagement with school practitioners is just as important as organizational frameworks to support innovative teaching and conducive structures at the system level. This book reflects this strategy and describes learning processes.