Actually Brien after I answered you I realized that this doesn't even require reference to the fair use dcotrine. You are wrong about the limitations on use. If you were correct I could not quote another author in my work critiscizing his writing.

But more to this point. Copyright protection extends only to a particular expression of an idea, not to the idea itself. It does not apply to a grading system although it would apply to the authors description of the grading system.

Below is an excerpt from some commentary in USCA (United States Code Annotated).

I would leave an interpretation of whether the specific material you are refering to is in fact a copyright violation to someone more familiar with the area, but the issue is from as clear as you suggest. My gut instinct is that C/W could do nothing to stop this if they wanted to.

Nature of Copyright. Copyright does not preclude others from using the ideas or information revealed by the author's work. It pertains to the literary, musical, graphic, or artistic form in which the author expressed intellectual concepts. Section 102(b) [subsec. (b) of this section] makes clear that copyright protection does not extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.