We spent a goodly portion of today's Educational Psychology class debating whether it was ever okay for a secondary school teacher to have a political campaign sign (e.g. Obama, McCain, or Nader for President) posted in their classroom.
This sprung from a question about whether a teacher in today's public schools should attend to moral instruction of their students. (There seemed to be consensus that the answer was yes with regard to upholding the social contract of the classroom. With regard to issues beyond the classroom, it got a lot murkier very fast.)
It spawned related questions such as: "Is there a difference between telling my student I'm a cat person and telling them I'm a Democrat?" and "How might conditions such as the age of the student or the subject matter of the class influence the answer?"
The basic tension seemed to be between the desire to have open and honest relationships with students and the desire to avoid alienating or creating an unfriendly environment for any student. Or, as one classmate put it succinctly, "Disclose or Impose".
The key discriminator seemed to be the power differential between teacher and students -- the age, experience, authority, and maturity differences.
In some situations, a disclosure of a teacher's political affiliation could make the students feel that they should conform to that affiliation, or feel alienated if the chosen affiliation is hostile to something essential to their identity (do I support an anti-immigration candidate in a classroom full of immigrants? or an anti-gay party in a classroom with LGBT students? or a pro-choice candidate in a classroom with pro-life students?).
In other situations, students might be curious about the background and biases the teacher brings to the discussion while being independent and secure enough in their own beliefs to not feel pressured or threatened by the teacher's affiliations.
In other words, the answer is clearly different for a sixth grader and a college student, with high school students in a mushy zone where the answer probably depends on the maturity and independence of individual students and the atmosphere of mutual respect and trust the teacher has (or has not) established with the students to counteract the implicit power gradient. The answer could also depend on the relevance of the teacher's political affiliation as a potential source of bias in the classroom discussions -- it could be different for the history teacher, the science teacher, and the music teacher.
At the end of the day, I think it's fine to say that I, as a teacher, should not use my publicly-funded teaching space to advertise for my political candidate of choice, but should be allowed to use my discretion on when it would be educationally helpful or harmful to verbally share my political affiliation with my students.
But what about the (hypothetical) bumper sticker I put on my privately-owned car three years before I thought of entering the teaching profession, and now drive to the middle school parking lot every day?