(a) “Required instructional materials” means any materials which a student must procure or possess as a condition of registration, enrollment or entry into a class; or any such material which the instructor determines is necessary to achieve the required objectives of a course.

(b) “Solely or exclusively available from the district” means that the instructional material is not available except through the district, or that the district requires that the instructional material be purchased or procured from it. A material shall not be considered to be solely or exclusively available from the district if it is provided to the student at the district's actual cost and:

(c) “Required instructional materials which are of continuing value outside of the classroom setting” are materials which can be taken from the classroom setting, and which are not wholly consumed, used up, or rendered valueless as they are applied in achieving the required objectives of a course which are to be accomplished under the supervision of an instructor during the class.