The vague language of several sections of this bill open the door for a single opposition to a book's content to outweigh any voices (even if they're a majority)who deem a book appropriate.
Most schools already offer (with no repercussions) alternate texts for any family to opt out of certain novel studies, as Librarian, I have instructed my teachers to always be prepared with alternate texts/activities for class novel studies. This is also problematic for students who are registered for AP courses as many of the "classics" on the AP exam reading list contain sexually explicit content, this law would intimidate teachers including novels that students may encounter on the exam and the difficult topics that they may be required to discuss.
The vague nature of "Library materials are considered instructional materials when used (i) for the completion of an assignment" inhibits students from self-selecting books that most interest them for assigned independent reading. As most school libraries contain upwards of 10,000 titles, it is impossible to alert parents/guardians to every title they may deem inappropriate--though they have access to our online catalog and can use it to have private discussions with their students. It's also unrealistic to say that Librarians will be able to alert parents to their student's independent reading choices when students are most often brought to the library for a 30 minute visit.
It is up to parents/guardians to teach their children what they expect, school staff can't possibly manage these choices for every student and no parent/guardian should be able to decide what another parent/guardian's child should be allowed to read.