The concern presented by parents regarding offensive/explicit material being taught to their children without their knowledge is understandable, but requiring teachers to identify every passage that may be considered offensive by a student is unecessary. What's considered offensive to one parent may not be to another; therefore, it's nearly impossible to determine what can be omitted and what can't. Also, material that is clearly explicit and offensive, such as the Holocaust and slavery, shouldn't be able to be opted out of. History is history. It happened, and it's the job of public education systems to educate students, not try and shelter them from knowledge of the past. While I agree that the parent is an integral part of a child's education, what's taught to students should be at the discretion of the teacher. In my experience, teachers already do as much as they can to limit the offensivness of questionable material. Allowing a student to completely omit the lesson from their learning experience will limit their knowledge later on in life when they may not have the opportunity to ask questions or obtain information from a reliable source like they can in a classroom setting. Aside from the effects later on in life, alternative materials must be provided on state tests and assessments which may cost additionally both state funds and time.