I reject this proposal.  Although it's intention seems simple enough, I beleive it is the first step in censorship of not only controverisal materials in books (can we define controversial material?) but controversial thoughts and ideas discussed in schools.  If we are to prepare students to be thoughtful, well-informed and critical-thinkers as a part of a functional democratic society, then students must have the opportunity to understand controversial topics and research them.  This regulation is fear-based and not commonsense.  If parents are afraid of the topics we teach in public schools, they are welcome to keep their children home.