About Marking a Short Story...
Say the criteria are:
a) - the understanding of the stimulus provided.
b) - the understanding of the conventions of short story writing.
c) - the use of language suitable to form and purpose.
If a teacher marks you down in a short story for 'some' lack of description (2 marks in a 20 mark story), does that fit the criteria given and is it appropriate to take marks away?
It's understandable that you are frustrated with your grade -- many students when they first receive a copy of a marked assignment have similar reactions. The first issue is that you are thinking of marks as "taken away" -- which is not how they are actually assigned by teachers.
Your work *starts* with a 0. Then, as the teacher goes through a rubric, marks are gradually added according to criteria set out in a rubric, depending on how well the assignment fits the grading criteria and the overall quality of the work. Teachers will sometimes make comments to explain parts of the marks, but often, given class size and grading loads, it's impossible to comment on every aspect of a story and still hand them all back on time.
Adequacy of description would affect both the criterion of "conventions" and that of "language". There may have been other issues as well with the story.
A grade of 90% is very good -- to do much better, you would need to be a perfect writer, significantly better than most other students your teacher has seen in her teaching career.