All you need to know about the sad state of public education is contained in two graphs I made up (with the help of my buddy Excel) based on data I painstakingly collected from S&P's Schoolmatters for the state of Pennsylvania.
The first graph plots student achievement vs. instructional expenditures for the 501 school districts in Pennsylvania.
The correlation between instructional expenditures and student achievement at these funding levels is random (R2 = 0.0013). Below the median (about $6700) we have a scatterplot. Above the median we see the residual effects of SES sneaking in. Above the regression line we see a lot of affluent school districts who have fallen prey to their monopoly rent-seeking school districts. Below the regression line we see mostly big city districts with lots of state and federal funding being pumped in and having little affect on student achievement.
These effects become clearer when we go to the next graph, student achievement vs. median household income:
The correlation between household income and student achievement is 0.42. That's a pretty good effect size for the social sciences. The data is a bit noisy because the PSSA data (which I'm using for student achievement) is not a very good measure of student achievement and the household income data is community based data, which may not correspond exactly to the student's household data. Nonetheless, it's pretty clear that family income is a good predictor of academic success. An even better predictor would be parental education, which I'll scrounge up soon hopefully. The best predictor would be student IQ, but we don't have that data.
So when Affluent School DistrictTM claims that they educate your kids better, thus justifying the high tax rates, you can tell them that their value-added is minimal. Their performance is mostly the result of student ability. They've been dealt a better hand. Same is true for the supposedly bad schools at the lower end. Their performance is a product of the students they get.
The affluent schools don't do a much better job with their poor and minority kids and the bad schools would do almost as good a job with the higher ability kids. The fact of the matter is that in the end most schools teach the same hodge-podge of faddish crap. A few really good teachers doesn't make much of a difference, education is the by product of many teachers over the course of many years. It all evens out.