Goldwater Institute: Does a certificate make the teacher-or results?

By Matthew Ladner, Ph.D.


This chart from the Brookings Institute may be the most important piece of education data I've seen in some years. The chart shows how teacher certification pedigree affects student performance in Los Angeles. Meaning, it shows whether traditionally state-certified teachers really are more effective in the classroom.

First, notice the incredible variation in performance by teachers. The most effective teachers, clustered on the right hand of the bell curve, move their average students up about 14 percentile points. Moving a classroom of kids from average (50th percentile) to well above average (64th percentile) is quite a feat.

Now look at the left side of the bell curve. These teachers are dragging their students in the opposite direction by approximately the same amount. These teachers took their children at the 50th percentile and dragged them down to the 35th.

Tragically for the students, we have a system of compensating teachers that insists on treating all types of teachers the same, and makes it difficult to remove the sub-par teachers from the classroom.

Finally, take a look at the three bell curves-traditionally certified teachers, alternatively certified teachers, and uncertified teachers. Notice the microscopic differences in student performance between those three groups of teachers, but the gigantic differences between the effective and ineffective teachers.

The implications are clear: principals should be free to hire whomever they think best suited for their schools regardless of certification; progress should be measured over time; and effective teachers should be rewarded, and ineffective teachers let go.

Dr. Matthew Ladner is vice president of research at the Goldwater Institute.