Opinions about whether comments, grades, or both are the most effective forms of feedback vary widely among teachers, school leaders, and even grading and assessment consultants. Thomas Guskey maintains that the truth is not as clear-cut as some suggest. He reviews the research, going back to the 1950s, to better understand when certain types of feedback are most useful. He concludes that grades and comments are not, in and of themselves, beneficial to student learning. Effective feedback, whether in the form of grades or comments, must give students a sense of where they are and what they need to do to improve.