An examination of National Assessment of Educational Progress (NAEP) results by the Economic Policy Institute's Richard Rothstein found that while disadvantaged students made significant progress in the last generation, their progress has actually stalled since NCLB and its test-based accountability measures were enacted 10 years ago.

No Child Left Behind's original goal of leveling the playing field for all students is still critical. We have an obligation to provide all children with the best public education possible. And the stakes have never been higher. According to a recent Stanford University study, the achievement gap between rich and low-income students has increased by 40 percent since the 1960s. It is now double the gap between blacks and whites. We have 3 million more children living in poverty than at the start of this recession. At the same time, we've cut more than 300,000 education jobs.

So where do we go from here?

I'm not here to say it's easy -- it isn't. This is complicated work, and there are no silver bullets or quick fixes.

Proper accountability is vital. But current accountability mechanisms for public schools don't gauge good teaching or deep acquisition of knowledge. For example, the Common Core State Standards, and the assessments being developed as part of their implementation, can help bridge that divide by focusing on deeper understanding of core content, which students then can apply broadly.

Nations that outperform the United States have gotten this balance right -- emphasizing teaching and learning as opposed to testing and blaming. In Singapore, for example, where I spent time with teachers and students earlier this year, schools are focused intently on growth and achievement. However, as I observed numerous diverse groups of children deeply engaged in learning, I saw nothing that could be construed as teaching to the test.

The good news is that we don't have to travel all the way to Singapore to find schools and districts getting it right. There are districts here in America that embrace shared responsibility and collaboration among teachers, administrators, parents, and the community. They've implemented evaluation methods premised on continuous improvement, not on testing targets. They've implemented ongoing professional development programs and built in time for teachers to plan, engage, and learn from one another.

These districts are developing rich curricula grounding students in areas ranging from foreign languages to physical education, civics to the sciences, history to health, as well as literature, mathematics, and the arts. And they've focused on wraparound services to help mitigate out-of-school factors that impair the ability of children to learn.

New York Times columnist Nicholas Kristof recently called our collaborative efforts in New Haven, Connecticut "jaw-dropping" and said that "New Haven has arguably become ground zero for school reform in America because it is transforming the system with the full cooperation of the union."