Student achievement varies widely across developed countries, but the source of these differences is not well understood. One obvious candidate, and a major focus of research and policy discussions both in the United States and abroad, is teacher quality.
Research and common sense tell us good teachers can have a tremendous impact on their students’ learning. But what, exactly, makes some teachers more effective than others? Some analysts have pointed to teachers’ own scholastic performance as a key predictor, citing as examples teacher-recruitment practices in countries where students do unusually well on international tests. One oft-cited statistic notes that high-scoring Singapore, Finland, and Korea recruit their teacher corps exclusively from the top third of their academic cohorts in college; by contrast, in the U.S., just 23 percent of new teachers come from the top third of their graduating class.
