Take my example from Negotiating Critical Literacies. It's better if you read the book. It's here.
It's kindergarten-age kids.
The teacher never declares herself to be a leftist or anything; the kids' environmentalist/anti-corporate/pro-vegetarian agenda seems to somehow come from the children themselves, not from the teacher.
(Note: In any classroom, the group's agenda forms in a way that trumps individual agendas, a problem in any democratic system.)
Maybe it does indeed come from the kids' initiative, but the teacher certainly guides/molds/stimulates it, so the question of initiative gets blurred.
The problem is that the kids' agenda seems to turn out to be very leftist in a way that elicits suspicion; is it really a coincidence that the kids' views happen to coincide with the teacher's views (which I understand to be leftist, even if she's not open about it)?
What if you implemented this "Freirian" educational philosophy, and soon you had little kids becoming gun-rights activists too, when they happened to have a right-wing teacher (probably quite rare for teachers to be right-wing)? My guess is that the second that happened, people would FREAK out. The only reason they don't freak out about the environmentalist stuff is that they happen to AGREE with it.
That's the idea, anyway.
I know that kids like rainforests/animals and stuff, so maybe the comparison between environmentalism and gun-rights is inappropriate, but it drives home the point that "political" education turns the kids into political pawns for their teacher's political agenda/ideology--and that's apart from the question of whether they should be the pawns of ANYBODY's political agenda/ideology.