This is a guest post from Nadia Zananiri, who teaches AP World History at Miami Beach Senior High School, and serves as AP World History mentor teacher for Miami Dade county. She is founder of the Facebook group Florida

Parents and Educators for Legislative Change.

I am not a private school teacher yet; but I am planning on becoming one. I have taught at a wonderful public school with a college prep program that allows all students access to a world class education for my entire teaching career.

I teach in an urban area with a mix of students. In the Advanced Placement classes I teach, I have students from some of the wealthiest neighborhoods in the country, to some of the poorest. Families that have been here for generations, to families who are recent immigrants and the parents don't speak English. Regardless of their background, my principal likes to always say "we have the best students in the world," and we do.

Many of my students' parents are wealthy and could easily afford to send their children to exclusive private schools, yet they choose to send their children to their local public school because they believe in public education. They have not bought into the hype that all of our public schools are in crisis. That all public school teachers are lazy and incompetent and that they cower in their classrooms scowling at their students, all the while waiting to collect their larded pensions.

During the nine years I have been teaching at my public school, the school has received grades of D, C, B and finally this year we achieved an A. Next year, due to the state of Florida changing the grading standards (which they have done every year since they decided to grade schools) we are projected to become a C school. The State Board of Education has reached the absurd conclusion of expecting special education students and English language learners to reach the same proficiency levels as regular students; and that out of date science test scores should be used as data (doesn't sound very scientific to me). Whichever grade the state decides to assign my school, I will know the truth, we are still an A school.

So why am I planning on leaving such a wonderful public institution for a private school? Well, I wasn't. Even after the state Legislators decided to exempt Advanced Placement classrooms from the twice voter approved class size amendment, and my student work load ballooned to 190 students without any extra pay, I was planning on staying.

But after the last faculty meeting, the state dealt the final blow to my teaching career in Florida public schools. We were told about the wonders of a magical algorithm that would be able to predict student growth. It's called the "value-added model." I refer to it as voodoo mathematics. If teachers do not meet the predictions of student growth projected by the algorithms in relation to their peers, they will be rated "ineffective." Teachers are ranked on a curve, thus a certain percentage will always be considered failures.

When the value added ratings were published in New York newspapers last week, many were surprised to see talented teachers ranked in the lowest percentiles. I was not surprised. One teacher of the gifted was ranked in the 6th percentile after her students' mean score dropped from a 3.97 to a 3.92. Students are placed in gifted and Advanced Placement classrooms because they have scored at the top range of state tests. If they are scoring high already, they will have a difficult time showing growth and statistically they are more likely to regress towards the norm.

Good teachers can now be fired because of bad math. As mandated by Race to the Top and the NCLB waivers imposed under current Secretary of Education Arne Duncan, which require districts and states to use standardized test scores as a significant portion of teacher evaluations, the Florida Senate passed bill 736 last spring. Under Race to the Top and Senate Bill 736, teachers with two years of "ineffective" rankings will be fired and their teaching license will be revoked by the state of Florida, thus banning them from teaching in any other public school in the United States.

Well, not exactly. These fired and banned teachers will probably be able to find work at a charter school where teachers don't have to have professional teaching licenses and are not subject to this new teacher evaluation system, despite the fact that charter schools also receive public funds. The exemption of charter school teachers from both the state and federal mandates, leads one to believe that politicians are less interested in accountability than they are in busting unions and making sure no teacher lasts long enough to collect a pension. In the name of firing the worst teachers, we will be firing some of the best.

I refuse to be a victim of the Russian roulette nature of value added models. I will not let myself be labeled an "ineffective" teacher after continuously striving to improve my instruction, my knowledge base, my relationship with my students and parents. I will not be labeled an ineffective teacher after spending hours on the phone, in person and over email contacting parents over skipping students, sick students, struggling students, amazing students....I will not be labeled an ineffective teacher after spending hours on my weekend and evenings grading student papers when I should be reading to my own young children.

I can't play by the rules of your game. It has reached the point where I know that I will inevitably end up a loser, no matter how hard I work. Private schools have become the Promised Land. Small class sizes, no government testing, unscripted curriculum and only accountability to my students, parents and administrators. I am a proud product of public schools from elementary to university, but the policies imposed in recent years by politicians are destroying the same system politicians claim to be saving.