How Many Teachers Does It Take To Close An Achievement Gap?
Over the weekend, New York Times columnist Nick Kristof made a persuasive argument that teachers should be paid more. In making his case, he also put forth a point that you’ve probably heard before: “One Los Angeles study found that having a teacher from the 25 percent most effective group of teachers for four years in a row would be enough to eliminate the black-white achievement gap.”
This is an instance of what we might call the “X consecutive teachers” argument (sometimes it’s three, sometimes four or five). It is often invoked to support, directly or indirectly, specific policy prescriptions, such as merit pay, ending tenure, or, in this case, higher salaries (see also here and here). To his credit, Kristof’s use of the argument is on the cautious side, but there are plenty of examples in which it used as evidence supporting specific policies.
Actually, the day after the column ran, in a 60 Minutes segment featuring “The Equity Project,” a charter school
