no child left behind

A new study says top-performing teachers turn out students who learn more than the students who had the worst teachers. And that extra learning has a huge impact on earnings -- and the nation's economy. Still, some educational experts say the study raises more questions than it answers.

No Child Left Behind has been a controversial change to the nation's educational system, but it has been good to me. Every state is now required to give a set of tests to track the student's progress, spawning an entire industry to score these exams. These companies hire tens of thousands of people...