Why Is It So Hard To Make Teachers Better?

In the last four decades, student-teacher ratios and class sizes have fallen dramatically. A majority of teachers now have master’s degrees. Spending per student has quadrupled, after allowing for inflation. Teacher experience is at postwar highs, and few teachers lack formal certification.

Despite all this, student performance today is roughly the same as it was in 1970. This is in large part thanks to the inability to improve the quality of our teachers.