The rhetoric about public eduction in Tennessee seems to be contradictory and confusing. Comparing State spending per pupil on a national grid without comparing per capita income and cost of living as factors is slanting information. How can a State with one of the highest graduation rates nationally have a population where 44% cannot read above the 3rd grade level and (I believe) that the study showed that about 1/4 were high school grads? I can remember years ago when "Church Schools" were considered a second class" education, not so today. Private schools are successful because the parents of the children attending them have a financial interest in the school and are motivated to be "hands on" parents when it comes to education their child. The day of a strong PTA group in grade schools seems to have faded. High school parents are directed more and more to be fund raisers for each sport,band, drama club, cheer leaders etc. Another thing about private schools seems to be that they are not under pressure to be as "politically correct" as public schools and don't seem as prone to "social promotions" If a child is not promotable they don't pass to the next grade and the tuition paying parent leans on the student, not the teacher or the system.
It's very important to keep in mind that teacher's Unions represent the interests of teachers, not the students. The unions have strongly opposed charter schools and vouchers for several reasons: (1) it diverts money from public schools, which is where almost all of their members teach, (2) if parents and students are given vouchers, they will leave 'failing schools,' which threatens the job security of the teachers working in the failing schools, and (3) teacher's unions have a very liberal social agenda, and they want your child in a public school to they can indoctrinate your child into their liberal ideology.
I've seen teacher's unions sacrifice the public school students time and time again for their own personal gain. It's so sad. If you've never watched the movie 'Waiting for Superman,' you should. It's a great movie that shows how little concern the teacher's unions have for children in general.