As used in this subchapter, “public school fraternity, sorority, or other secret organization or society” means any type of organization or society that fosters undemocratic practices and seeks to perpetuate itself by taking in additional members from the pupils enrolled in that school or local school system on the basis of the decision of its membership rather than upon the free choice of any pupil in the school who is qualified by the rules of the school to fill the special aims of the organization or society.