Our Take: As a new school year approaches, the Christian Science Monitor examines the current methods of teacher evaluation, especially in light of President Obama's Race to the Top program, which ties teacher ratings to their students' test scores:

Research indicates that the quality of teaching has more impact on student learning than any other factor that a school can control. A year with a good teacher, studies show, can mean a child learns as much as three times more than a student with a poor teacher.

But the mechanics of quantifying good teaching are tricky. How can districts discern who the best — and worst — teachers are? Are test scores reliable? Is observation too subjective? How does something as subtle and nuanced as teaching a roomful of individuals — a job that is arguably more art than science — get reduced to a score?