Whereas the best public-school systems in the world—Finland, Singapore, South Korea—recruit all of their teachers from the top third or better of their college graduates, in America the majority come from the bottom two-thirds, with just 14 percent of those entering teaching each year in high-needs schools coming from the upper third. And the numbers may be getting worse. According to a recent survey conducted by McKinsey, a meager 9 percent of top-third graduates have any interest in teaching whatsoever.