The problem is that in comparing public schools to private schools, you are comparing apples to hamburgers.
Public schools, by law, have to take everyone. No one can be turned away from a public school. This applies to children with learning disabilities, mental disabilities, or social disabilities. Those children have to be provided with an education. Private schools have no such regulations. Give the two entities equal populations from equal backgrounds before making an assessment of which is better.
Another interesting fact to note about this move to prove public schools don’t work is in the inner working of No Child Left Behind (NCLB). According to NCLB, children must be tested on grade level with their peers. At my old school, 8th grade special needs children had to take the State Curriculum Test for science. Why was this unfair? The 8th grade special needs children DID NOT TAKE 8th GRADE SCIENCE! They were not able to. Much more attention was focused on getting them ABLE TO READ ON GRADE LEVEL! We also had ESL(English as a Second Language) students who had just immigrated to America having to take the English and Reading exams FOR A LANGUAGE THEY COULD BARELY UNDERSTAND! When the test results come in, the results were predictable. My new school has been unable to make Adequate Yearly Progress because when you make high scores to begin with, you can’t really go any higher up. So you end up with schools that rate really high one year and really low the next. When schools score low, punishments will follow…such as loss of funds. So you take a poorly-performing school, many of which are already under-funded and you cut their funding.
Test scores measure one thing: how a child performs on a test on a given day. They are not an accurate assessment of student learning, nor are they an effective tool to show what schools work and what schools don’t.
NCLB was designed to “prove” that public schools don’t work using one criteria: test scores. This is what happens when you have a career “C” student who got by because of who his daddy was making education policy.