Unfair marking?

In the country where I attend the school the marks are from 1 to 6, with 6 being the highest but only for those who know more than what is required by the teaching programme. At geaography, I have 3 marks: a 5, a 2 corrected to 5 and a 3 - and my semester grade is 3. Isn't it unfair?

I’d like to tell you people that my geography teacher is commonly considered among students and graduates to be unfair at marking and maintaining the lessons.
Maybe there’s a conspiracy at my school?

One way to get good grades is to act like a dumbass most of the time, then when you do a higher quality of work the teacher is impressed and gives you a higher grade.
If your high school has a credit system of some kind take a look at who has the most credit, at my school it was the dumb kids. The students who do a high quality of work all the time are forgoten.