They have your kids for 8 hours a day, which is a whole chunk of time to inculcate their way of thinking.
Problem is they have done it in such a hidden way that parents, students and even the teachers have no idea how it takes place.
I discovered this aspect of the immorality-amorality teaching in 1984 and kept all four of my children out of public school preferring private school and homeschooling.
Not to mention the rampant sexual abuse by teachers in public schools.