The teachers and educators may not be the best but he real problem is that big city and inner city schools (white, black and other minority) students on the average have an IQ of 85. At this IQ level one half cannot graduate from a regular high school.
You may dumb down the standards or just give them a diploma but it will mean little or nothing. Employers have learned this and that is why they look for "some college" or college graduates.
Whenever I tell this to a teacher they accuse me of misfeasance at the very least. A good summary of this issue of urban flight and IQ can be found: HERE
As much as I like President Bush, "No Child Left Behind" is doomed to failure not because of the teachers or the educational system but becasue of basic human nature and its inequalities.
Skills introduced in the lower grades can be acquired by most everybody, and that is where Bush is. Levels attained do correlate with IQ, and you say, but that does not absolve primary schools from teaching normal children to read and calculate. I did not kmnow the 85 number for HS grad, but I do know that college grad is 120.