NY Times Editorial:

The No Child Left Behind Act broke new ground when it required the states to educate impoverished children up to the same standards as their affluent counterparts, in exchange for federal aid. The law did not just drop out of the sky. It represented a deliberate attempt by Congress to ratify and accelerate the school reform effort that swept the country in the early 1990’s, when the states began to embrace standards-based accountability systems that quickly showed promising results.
The achievement gains have fallen far short of what Congress hoped for when it passed the landmark federal law — and also far short of what the country needs to keep pace with its economic rivals. In addition, student performance has flattened in recent years. In many cases, that is because states that reaped all of the early, easy gains that are typically achieved by merely paying attention to a long-neglected problem failed to do the tougher work necessary to sustain their reforms.
Recent studies offer sobering news about the challenges that lie ahead. Happily, there is also encouraging news from the states that have stayed the course and continued to build rigorous, standards-based reforms.