The "Best of Both Worlds" Myth

Most teachers assume that providing both a grade and a comment is the ideal strategy. The logic is that the grade tells the student where they are, and the comment tells them how to get better.

The "Washing Out" Effect

The research proves this logic is flawed. When a grade is present, it "washes out" the beneficial effects of the comment. Wiliam explains the typical student reaction:

1. They look at the grade.

2. They look at their neighbor's grade ("What'd you get?").

3. They ignore the comment.

The grade acts as a "stop" signal for thinking. Once the student knows their score and their social standing relative to peers, the learning process ends. They do not engage with the diagnostic advice.