Unlike non-witching schools, there is no set scale of marks you can get. The best mark a witch can score is a Z----------------------------------, etc. The minuses or plusses on a letter can go on forever. This is why it pays to get a good teacher, as if you are a star student, but your teacher doesn't like you, she might give you an A+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++, which is really equivalent to a Z-, but will show up in your report card as an A. while this practice is highly discouraged, it is not illegal, much to the dismay of some students. This shows the utmost importance for a witch to stay on their teacher's good side during school, and always blame their misfortunes on another student.