This respected body shouldn't concern itself in legislating the slippery slope of "morality," which is central to the legislation.  You aren't so much keeping parents aware, as you are threatening teachers with spooky, ambiguous language.  Who is to say what is controversial?  

Schools already have a rigorous process in play that vets material for its educational merit.  Additionally, the new push in education is to teach multiple texts in a classroom.  This method allows the teacher to differentiate and give options to students, thus reducing the risk for a student feeling forced into a text that makes them uncomfortable.  Independent reading is also a major resource for the English teacher that also allows the student to differentiate to literature that makes them comfortable based on rigor and topic.    This legislation could easily be interpreted as a means to ban any literature not expressly delineated in the syllabus. Therefore you would limit the number of texts a teacher would be willing to show a student, which would actually increase the likelihood that there would be a concern.  More to the point, you would also be more likely to discourage reading altogether.  

Teachers are constantly looking for opportunities to connect with students.  This often requires the teacher to know their audience and improvise during the year, well beyond the point of submitting a syllabus.  The limiting language of this legislation would make it impossible for a teacher to improvise the curriculum to better meet the needs of the student without fear of reprimand.   This would hurt students since it puts extraordinary limits on how a teacher may connect students to content.

All in all, it would do more harm and no good.