Matthew Chingos:

The fact that teachers with master’s degrees are no more effective in the classroom, on average, than their colleagues without advanced degrees is one of the most consistent findings in education research.  In a study published in 2011, Paul Peterson and I confirmed this finding by comparing the student achievement of the same teachers before and after they earned master’s degrees, and found no impact.

This finding may be non-controversial among researchers, but it has largely been ignored by policymakers.  Ninety-six percent of the 112 major U.S. school districts included in the National Council on Teacher Quality (NCTQ) Teacher Contract Database pay teachers with MA degrees more than those with BA degrees, with an average difference of $3,205 in the first year of teaching, $4,176 in the fifth year, and $8,411 at the top of the salary schedule.  The size of this pay bump varies widely, topping out at over $30,000 in three districts in Maryland.