typicalsypnosis

The notion that grades are an accurate representation of your intelligence is ridiculous. 

Exams and tests are stressful, and for any kid wanting to do well there can be a lot of anxiety around this. This built up worry and tension can cause lack of concentration and will lead to a poor performance. Many kids also have a lot of pressure from parents to do well. 

Grades are usually determined from a single test. There are many factors that could affect the grade. For example, the situation at home. A kid may have parents who were up late fighting and the kid didn't get enough sleep. A kid might lack the resources and support that they need to properly study and prepare for a test. 

Furthermore, on the day of the test there could be many reasons why performance is impacted, such as sickness, being undernourished, dehydrated, tired, anxious etc. 

I am an all round good student who usually achieves good grades. I study lots and perform well most of the time. But even in instances where I have studied and prepared for the test, on the day it doesn't always go as planned and some grades are not a good representation of my ability.