These guys make me tired.
The moral decay starts at the top... the administration of the district and county offices.
I object to most sweeping generalizations, this one included.
Here is a more objective opinion, from someone who has worked in the public school system in a liberal state for many years: Some teachers have a political agenda in their everyday lessons, but not a majority. Most teacher unions (like most unions of any sort) have a liberal political agenda.
That said, most teachers in public schools care very much for the academic welfare of their students, and spend their time educating kids from a vast array of backgrounds--good homes, bad homes, brilliant minds, learning disabilities...they don't have the option of refusing to educate troublemakers; don't have the ability to pick and choose students like private schools; and don't have the advantage of one-on-one teaching like homeschool homes.
From my vantage (not a teacher) I see a positive daily effort to instill knowledge and very little of the indoctrination that is so often touted by anti-public school groups.
Political indoctrination (like religious indoctrination--gasp!--) belongs at home, and parents and taxpayers are well within their rights to object to teachers who abuse their pulpits.
I just get a little tired of public school bashing at FR and elsewhere. The vast percentage of the time, public school teachers get the job done, despite the many obstacles.