How important are high-quality teachers? A few years ago the Brookings Institution published a paper, Identifying Effective Teachers Using Performance on the Job (PDF) in which three scholars looked at that question. The authors were Robert Gordon (Center for American Progress), Thomas J. Kane (Harvard University) and Douglas O. Staiger (Dartmouth College).
They calculated that simply having a top-quartile or bottom-quartile teacher could make a difference in 10 percentile points on a random student’s achievement.
That’s twice the gains produced by making classes smaller:
A random assignment evaluation of a classroom size reduction in Tennessee found that schools could improve achievement by half as much—5 percentile points—by shrinking class size in early grades (Krueger 1999). But class size reduction of the magnitude considered in that experiment is expensive: shrinking class size from twenty-two to sixteeen students per class would require a 38 percent in the number of teachers and the amount of classroom space in those early grades.
The authors also say there’s a great need to expand the teaching corps, simply to maintain current student-teacher ratios. To do that, they recommend:
- Let new teachers start on the job without paper credentials, which are of limited usefulness anyway
- Be more selective in granting tenure
- Give bonuses to highly effective teachers who work in high-poverty schools
- Measure teacher effectiveness, using multiple indicators
- The federal government should give states money to start projects to link student achievement with teacher effectiveness.
I don’t endorse everything in the report, but it’s not a bad place to begin. They say that reducing class sizes (and hiring more teachers) doesn’t have to dilute teacher quality. But that depends on changing the way we hire and then manage teachers–a tough nut to crack.