The course rating system would allow students to rate the effectiveness of a course.
The administrator would define the ratings that they would like to have per course. The administrator would have the ability to create multiple ratings (usability, flow, accuracy, etc).
Once the ratings are entered in, students would see the rating block at the top each course showing all of the ratings that the administrator has defined. They can then set the ratings (or modify if they have rated this course already).
The teacher(s) can login and see the averages of each rating.
The administrator can run reports showing averages per course or per teacher.
The scale of the rating system (1-5, 1-10, etc) can be hardcoded or set as a system wide scale by the administrator (preferred - config maybe??).
This would require at least two tables:
Ratings (define the applicable ratings)
CourseRatings (stores the actual rating values supplied by the students)
-UserId (student who rated the course)
Depending on how slick you wan the UI to be, the rating control could use stars and be ajaxed (see the telligent community server rating control).
This would also solve issue http://tracker.moodle.org/browse/MDLSITE-273.