It would be tough to find a slope that's potentially more slippery than this one: public schools setting different achievement expectations for students based on their race and ethnicity.

But that's exactly what's happening in dozens of states that have received waivers from the U.S. Department of Education, allowing them to replace the more onerous provisions of No Child Left Behind with more flexible accountability measures. NCLB's core premise was that all students - regardless of ethnicity, socioeconomic, or special-education status - would have to be proficient in reading, writing, and math by the 2013-14 academic year. States were given leeway in setting their definitions of proficiency, and in deciding how best to move students toward the final goal.