The feedback of teachers for their learners is most effective when it is based on statements of individual students, because feedback is quite often a reciprocal procedure. To obtain the possible impact, students must perceive the different forms and aspects of feedback as a help for further learning in an adequate manner. Teachers have to pay attention to the formulation, timing, and many other principles of feedback. In this context, an important asset is diagnostic assessment and the respective feedback, which should not be seen in contrast to but as a complement to learning-level assessment. Another distinction has to be made with regard to the different feedback procedures related to the content and the task, the learning processes, and the self-regulation of the learners. Hattie and colleagues show how teachers can induce the learners in different ways to give some sort of feedback about how they are able to benefit from the behavior of the teacher. This can be done at the end of a more or less extensive teaching unit.