Parents expect their children's minds be filled with knowledge when they go to school, but some teachers veer from their prescribed course of study and share personal opinions to try to persuade students to accept their viewpoints. This is not an issue of free speech. If controversial issues are discussed, teachers are required by district policy to share all sides of the issue.
I know of a situation last year in which a teacher frequently showed movies that had a political message. The teacher shared controversial personal viewpoints and downplayed students' opposing ones. One student, who felt uncomfortable listening to the teacher's personal views, confronted the teacher. The student's parents complained to the teacher and administrators. Fortunately, the parents had given this child a good moral foundation, and the teacher's views did not change the student's mind.
Because the teacher is an authority figure, some students, who may not be as well-grounded by their parents in moral principles, may adopt the teacher's personal views.
With the purging of faith-based values from public schools, students must accept relativism and secular humanism as the predominate worldviews. But this poses a dilemma for any student from a home with traditional family values. Should students have to put their values and beliefs aside in the classroom? Maybe students should wave a flag, so the teacher, in the interest of intellectual honesty, is reminded to share opposing viewpoints.
Parents must prepare their children for a possible assault on their family's values with the same forethought and diligence practiced when teaching them to look both ways before crossing the street.