I spoke with a friend yesterday whose girlfriend works for the teachers union. His take on Bush's NCLB program, based on info from his sweetheart, is that the program is really just an effort to kill public education.
If I understood correctly what he told me, a school must meet certain goals and standards, primarily through testing of students. However, no provision is made for students who don't speak English or have other problems. This tends to drag down the school's scores, especially if in a high-immigrant area.
If the standards aren’t met, some provision exists which the allows students to leave the school for another. (Sorry for my poor understanding.) Anyway, once students start to leave for better schools, i.e., private schools, the public schools will collapse under the declining enrollments.
I know that conservatives like school vouchers and that public school teachers tend not to, but I’ve never dug into it to understand the differences.