With all due respect to the lessons of experience, I prefer the rigor of evidence. When a trio of psychologists conducted a comprehensive review of thirty-three studies, they found that in every one, the majority of answer revisions were from wrong to right. This phenomenon is known as the first-instinct fallacy.
In one demonstration, psychologists counted eraser marks on the exams of more than 1,500 students in Illinois. Only a quarter of the changes were from right to wrong, while half were from wrong to right. I’ve seen it in my own classroom year after year: my students’ final exams have surprisingly few eraser marks, but those who do rethink their first answers rather than staying anchored to them end up improving their scores.