<p>How many students really look at an exam once it’s returned, other than to take note of the grade? I realize that grading errors aren’t unusual. Probably the people most likely to review the scoring are disappointed students trying to find a grading error in the other direction. In which case, of course, they’d be more disappointed to see that the true score was lower than the original.</p>
<p>Are they obligated to report it? Well, as Marian says, probably in a perfect world.</p>