Why do I start this list with the "B" paper? Because a B is a fine thing to get on a paper and because a B paper is a paper that fulfills the requirements of the assignment in full. In short, a B is the description of work well done. The A paper adds several positive qualities that surpass all the requirements of the assignment. Among these are clarity and richness in content. More detail is given below.
The B paper, then, is a complete paper in fulfilling the assignment, but lacks something in organization, clarity, richness of detail, quantity of information , or cleanness of style. If you receive a B on a paper, ask me what from this list describes what is missing. Often, the B paper is one revision away from being an A. The revision involves noticing the flaws and thinness in analysis, content, or style, and then moving vigorously to correct them.
Significantly adapted from Shaw, H.E. (1984). Teaching Prose: A Guide for Writing Instructors (pp. 114-154). New York: W. W. Norton.