These are individual research courses arrange between an instructor and a student to meet a special need. They are rarely offered to students who can fulfil their course requirements with regularly scheduled courses.
Sometimes an instructor will offer a reading course to a student who wishes to pursue a well-defined topic in depth. At other times, students who cannot be on campus regularly during the summer semester might take a reading course.
The content and grading requirement of the course is set by the instructor. Instructors are under no obligation whatsoever to supervise a reading course.