There are multiple problems with this amendment.  Let me just discuss a couple.

1. "Senstive" and "sexually explicit" are terms that are extremely subjective.  What is sensitive to one is not to another; the same goes for sexually explicit.  
2. As a high school history teacher, does this mean that I'll have to send a letter home when we discuss historically "sensitive" areas?  Michelangelo's statue of David?  The Holocaust?  Castration used as punishment?  Delacroix's painting Liberty Leading the People?  
3. This is just one more task that will be placed upon teachers, who are currently burdened with too much paperwork and beaurocratic red tape.  Minutes add up of you're asking me to compose a letter every time something in the textbook, reading, video, book, etc. might be construed as "sensitive".  This means less time to teach.

Please reconsider passing a law that will have many unintended consequences.  Let's leave it up to individual school divisions to make decisions about what is considered acceptable and unacceptable for their schools.  Many teachers already send out permission letters for certain things, but parents cannot shelter their kids from every "sensitive" thing in this world.  Either you trust teachers to  make sound decisions, or you don't.