SCHOOL FOR THOUGHT

The true value of teachers

A while back in our blog, there was a discussion of the legitimacy of judging teachers on the basis of the value they add to their students’ test scores (how much teachers raise or lower their students’ test scores, adjusting for the students’ characteristics). The main objections were that (a) the use of value-added assessment may unfairly penalize teachers who are assigned hard-to-teach students and (b) that student test scores are not a valid measure of teacher effectiveness.

Now comes a Harvard study that looks at these two objections. Tracking one million children from grade 4 to adulthood, the researchers tracked the impact of teachers who had already been identified as adding value (VA) on their students’ test scores and their students’ long-term outcomes.

Objection #1
The researchers found that “when a high VA teacher joins a school, test scores rise immediately in the grade taught by that teacher; when a high VA teacher leaves, test scores fall. Test scores change only in the subject taught by that teacher, and the size of the change in scores matches what we predict based on the teacher’s VA.”

Objection #2
The researchers found that “students assigned to higher VA teachers are more successful in many dimensions. They are more likely to attend college, earn higher salaries, live in better neighborhoods, and save more for retirement. They are also less likely to have children as teenagers.”

Among other things, the researchers found that “overall, our study shows that great teachers create great value and that test score impacts are helpful in identifying such teachers”. H/T LJCD