I had the same science teacher for 7th and 8th grade. I always got a C or a B. A group of girls always got A's. I told the science teacher when I was in 8th grade that he should give us a test from the previous year to see how well we remembered the material. One day he did just that, and guess what? My grade was the same as the girls who got the A's the previous year. They crammed, took the test, and forgot. I learned and retained what I learned. To me, grades are mostly an expected tradition to be followed, and gives us very little insight to what a student actually knows or can do.