"The only important thing about feedback is what students do with it," declares Dylan Wiliam in this article. The standard school procedure (in which a teacher looks at a piece of student work and writes something on it, and the student later looks at what the teacher has written) does not necessarily increase student learning. Teachers need to keep in mind that the purpose of feedback is not just to improve the existing student work, but to enable the student to do better work in the future. Wiliam describes how teachers can make feedback more useful by (1) assigning tasks that illuminate student thinking; (2) considering feedback as detective work for students, and (3) building students' capacity for self-assessment.