And there are lots of misconceptions about what grades are. Grades are not a measure of intelligence. Grades don't measure creativity. They are not an indication of your ability to contribute to society. Grades are simply a measure of how well you did on one test on one particular day.
Some people think that a test score measures what a student accomplished in a course.
This is of course false. A test score is a measure of what a student scored on a test. If you are anxious about a test and blank out, then the grade cannot be a measure of what you learned. Common thoughts are. If I fail the test , I'm a failure.