Should I write a letter of resignation from my teaching position?

[appleseed582]

Three of us at my school have been told that our contracts will not be renewed next year. We were told today that we could submit letters of resignation for the school board to approve when it meets in 2 days.

We are being forced out, because we advocated for special needs children to get service and the district is trying to keep kids out to keep costs down. We are non-tenured and are higher on the pay scale than newer graduates, so that is a factor as well. We have since discovered that the administration brags about hiring new teachers who are cheaper, but not keeping them around once they are close to getting tenure. The union is very weak and has no voice, so they can't help.

What are the pros and cons of writing a letter of resignation? If I don't submit one, what will the district do to me? Will not resigning keep me from getting another teaching job? What in the world do I say as to the reason for my resignation?
My union rep says the district likes to have letters of resignation so they can say it was the teacher's choice to leave. The board can then vote to accept them en masse with one vote and the issue is quickly and neatly resolved--for the district administration.