Sorry...this teacher, in my opinion, does not have the right to be in the classroom during this time. I base this opinion not on any beliefs as to whether or not transexuals are mentally-ill or simply people born as the wrong sex or anything like that...I don't think those distinctions matter in this debate.
What does matter is that a very obvious gender change (or a man dressing up in women's clothes, makeup, etc.) would bring up all sorts of questions about gender, sexuality, appropriate gender-roles, etc., etc., etc. in the minds of that teacher's students. These are things that are simply inappropriate for a teacher to bring up in class...whether intentionally or unintentionally.
While this teacher has the "right" to deal with his/her own issues...s/he does not have the right to confuse or influence his/her students on these matters.
If a teacher is going through a painful divorce...they have the right to experience all of the horrible emotions that go along with that divorce. They do not have the right to cry in class, bad mouth their husband to another teacher in front of students, or discuss their divorce or ex-husband with their students.
Why? After all, shouldn't that teacher have the right to go through their own personal experiences? Yes, absolutely...but they do not have the right to bring inappropriate conversations to their students...be it intentional or otherwise.
I do not have the right to talk about inappropriate things with another teacher during my planning period in the teacher's planning center with the door open...if a student overhears (even if I TOTALLY didn't mean the student to overhear) then I get into a lot of trouble. If I chose to discuss inappropriate issues with other teachers thats my right...but I simply do NOT have the right to discuss, bring up, or influence my children to discuss or think about inappropriate issues...its not my job. I shouldn't be talking with my students about my sexuality, my feelings on my gender, etc. and what this man is doing is basically talking about his sexuality and gender confusion with his students every day simply by being in the classroom.
This teacher is working through some serious issues. In respect for the fact that he/she might be a wonderful teacher, I would support putting him on medical leave until his "transformation" is complete, and then allowing him to return to a brand new class as "Miss," rather than "Mr." but I do not think that he has the right to bring up the issue of being a Mr. who is changing to a Miss with his class...which he does simply by being there...he doesn't even have to say anything.
This isn't about discrimination - its about what is appropriate for a teacher to bring up with their students. A teacher can be gay or straight...they just shouldn't be talking about their sex life with their students. A teacher can be transgendered, in my opinion, they just shouldn't be bringing up the issues related to being transgendered by undergoing the changes while in the classroom.