I can't say anything about current Sonoma County teachers, but when I was in school many years ago, there was certainly a disproportionate number of liberals.
I cannot forget one Jr. High English teacher, who explained "trickle-down" economics to us. According to him, money is distributed (somehow) by government, and it is given to poor people by Democrats, and rich people by Republicans. < begin teacher idiocy> Poor people spend it, and that's what keeps the economy going. Rich people don't even need it (because they're rich), and they'll just keep it all for themselves. It's plain silly to think that when the rich people have all the money, they'll spontaneously give it to the poor people, and that's why trickle-down doesn't work.</teacher idiocy off> That little gem was "taught" me in the early 70s.
I attended my wife's credential ceremony a couple of weeks ago for the education dept of a "North Bay College". The student speaker was no doubt selected to give the address because it seemed she was a model student to her leftist professors. Her talk consisted of the words "peace" and "social justice" and also referenced Ghandi. I also know that "muliculturalism," "diversity," and "social justice" are very much a part of much of the cirriculum of that education dept. I'm not suprised about these students complaining about leftist teachers, because that's mostly what the schools turn out.