Responsible parents try to. Once a child is out of the home, playing with other kids or in their homes, it is tremendously difficult to monitor the speech and images they are exposed to. I'm not saying give up on it, but parents must be aware that there are bigger boogeyman out there than the very large majority of teachers who are trying to teach kids. Plus if they ban books, they should ban all mention of any religious holiday. Parental rights and all.