The book introduces the concept of content-focused approach to analysing and improving instruction. Compared to current approaches, the focus on the content dimension of learning processes, which is the core of didactics, is more consistent. Didactics deals with the issue how to effectively teach and learn what is considered culturally worthy and personally meaningful, hence the focus on educational content. Educational content is not understood as a static set of items (to be) memorized, but as the overall educational potential of disciplines that pupils encounter during their time at school. The book appertains to the slogan quality of/in education. Quality is understood from the dynamic point of view – with regard to how teachers plan, realize, and evaluate instruction. The regard for quality – as the distinction between better and worse in the professional sense – is accompanied by consideration and justification of alternatives. With the aim in mind to offer teachers-reflective practitioners a systematic method for improving instruction based on its reflection, this book introduces the method of AAA (annotation, analysis and alteration). The method is illustrated with ten didactic case studies from different disciplines of school education with the prospect of generalization across domains. The authors believe that the book opens the way towards the improvement of instruction based on reflection, and with time towards a new (productive) culture of teaching and learning.