Politically-Motivated Teacher

There is always that one teacher, the one who is always bringing his or her politics into the classroom and is extremely passionate about it. Be it about religion, the government, or ethics, morality, and values, this teacher is always ready with their own arguments and/or long-winded speeches. Typically, this person teaches a class involving social sciences (e.g.: history, sociology, politics), but it can be any teacher in any subject. College professors are even more likely to be politically motivated.

The Politically-Motivated Teacher can be portrayed either as a positive or a negative thing, generally depending on whether or not the teacher's views align with the author's. If it's shown in a positive way, then the teacher will often stimulate intelligent debate, helping his or her students to think more critically about the events in the world around them and get more involved in society. If it's shown negatively, the teacher will run the classroom with an iron fist and punish students who voice dissenting political views instead of promoting discussion. Either way, expect anvils to be dropped like a bowling ball tied to a weak tree branch.

A Hippie Teacher can be related, for reasons of hippies being very politically radical. The negative version of this trope often takes the form of a Sadist Teacher with Strawman Political elements, while a positive version is usually a Reasonable Authority Figure.

This trope is definitely Truth in Television, as any college students (and sometimes high school students) can attest to. The political alignment of these teachers often correspond with the general atmosphere of the school in which they teach, though there are without a doubt many who go against the grain of their institution's political philosophies.

Film

 * Clueless has Miss Geist, who wants to inspire her students to save the environment and aid disaster victims. She's portrayed as dorky, but likable.
 * The teacher obsessed with Vietnam in Back to School brings a certain kind of psychotic passion to his classes.
 * "Mr. Tergeson's really committed. In fact, I think he was."
 * Mr. Keating from Dead Poets Society spends more time spouting Romantic and Transcendentalist ideals in his class than actually teaching.
 * The Women's Studies professor from Sorority Boys is a terrifying example of a Straw Feminist. Among the lecture topics in her class is the "Myth of the Male Orgasm," prompting a confused look from Dave, the only male in the class.
 * A mild example appears in Superman IV.

Literature

 * Justified in Robert Heinlein's Starship Troopers. The History and Moral Philosophy class every student is required to take attempts to implant pro-military beliefs and encourage joining the Federal Service, so the teachers naturally push these political and philosophical values on their students.
 * In Starship Troopers, he puts his money where his mouth is, resuming his commission with the Mobile Infantry.
 * A similar example is Kantorek in All Quiet on the Western Front, who encourages his students to join the German army in World War I, greatly romanticizing it as something glorious. Of course, he couldn't be farther from the truth.
 * Professor Dillamond in Wicked is extremely passionate about his beliefs about the prejudice against talking animals in the school system and his fears about what is happening to them. This has a profound effect on Elphaba, particularly because of the prejudice against her for her green skin.
 * The eponymous subject of Tuesdays With Morrie, Morrie Schwartz, was said to have been very much an activist, even giving his students all A grades to prevent them from being drafted.
 * Dolores Umbridge is a negative version who teaches Ministry propaganda and punishes students (and eventually teachers) for disagreeing with the party line.
 * An interesting subversion in Avi's Nothing But the Truth, in which everyone except the teacher (and the student that the book focuses on) has an agenda.

Live Action TV

 * Square Pegs had a Vietnam veteran turned football coach who obsessively compared every event on the football field to Vietnam, and blamed the team's defeat on the treacherous liberal media.

Web Comics

 * In the early arcs of Better Days Fisk had to deal with a particularly anvilicious liberal social studies teacher.

Web Original

 * Quite a few Urban Legends archived and discussed on Snopes have such teachers, typically involving them teaching a lesson to their students or getting into a fracas with a student of a different political alignment. A few examples (of varying degrees of truth) include a professor giving his students a hands-on lesson about socialism, a teacher having veterans come into her class to impart patriotism to her students, and a Hollywood Atheist professor attempting to disprove the existence of God...by dropping a piece of chalk.
 * The latter of these also mentions a similar Chick Tract.

Western Animation

 * Bobby's History teacher on King of the Hill is ridiculously pushy and political.
 * South Park's Mr. (or Mrs. Garrison has been known to do this on occasion, though less blatantly, as it's often left to offhand comments (such as in The Movie when he declared the Mothers Against Canada were "probably just all on their periods"). In "Follow That Egg!," however, (s)he manipulates the lesson in a ploy to keep gay marriage illegal (though his/her motivation is more personal than political).
 * The Fire Nation schools in Avatar: The Last Airbender are staffed entirely with these sorts of teachers, whose lessons all carry a heavy undercurrent about how wonderful their country is and how their imperialism is for the good of the world. This has less to do with the teachers themselves and more the Fire Nation seeing that these values are imparted to the younger generation. Since the Fire Nation has been in this state for a hundred years, it's likely the school was like this before the current faculties were ever old enough to attend. All of this is Truth in Television of course, as mentioned below.

Real Life

 * Andrew Schlafly, creator of Conservapedia, is a teacher who greatly encourages his students to use his website for research. The site is pretty up-front about having a strong conservative bias (the idea being that it is opposite to the purportedly liberal Wikipedia). The site itself is, against his wishes, practically a parody of itself due to the number of Trolls who've infiltrated it.
 * There was a minor kerfuffle a few years ago when a high school history teacher named Jay Bennish was recorded going on an explosive political tirade (remember, this was history, not current affairs), and suspended as a result. Bennish claimed he was trying to get his students to "think more in-depth," an explanation that didn't really gel with the nature of his rant.
 * Ron Jones and his "Third Wave" experiment, intended to teach his students on Nazi Germany and the dangers of fascism. It was later adapted into a Made for TV Movie, a book, and a German cine film.
 * The schools of any totalitarian government exist almost solely to instill their political philosophy into the next generation, or when they don't have one, indoctrinate students into the personality cult of the Glorious Leader.
 * In the United States, universities are often accused by conservatives of being centers of liberal indoctrination. To be fair, there are numerous studies that come out in which the college's liberal-leaning teachers outnumber the conservatives by absurd numbers.
 * Which is easily explained by the fact that for a conservative academic, there are much better options than becoming a university professor, mainly in the numerous conservative think tanks.
 * Some argue that the reason so many conservative think thanks exist in the first place is due to conservatives being driven out of universities.
 * Ward Churchill is one of the more infamous real life examples. Although to his credit he was an ethnic studies college professor. He just took being outspoken and opinionated to whole new levels