Julia,
No challenge at all. If you do not like the term
cartel, then how about
monopoly?

I'm referring to the official bureaucracy - AFAIK, there is one in every state - as well as the federal Frankenstein, the DoEd ,that oversees
who gets taught,
what they get taught,
how it is to be taught and
who may do the teaching.
The cartel [monopoly | bureaucracy] will tell the home-schooler what they must teach and will decide whether or not you are qualified to teach their own children, and it will decide what text and materials you may use. Ditto for the private school.
The cartel [monopoly | bureaucracy] dictates that I may not serve as an instructor of science or mathematics - except as a substitute on an emergency basis - despite my credentials because I have not had the appropriate courses in theort of education fluff, etc., yet I am qualified to teach in my academic field in any college you might care to name...including those dedicated to the training of teachers.
