Big Study Links Good Teachers to Lasting Gain

This New York Times article discusses recent research which shows that good elementary and middle school teachers (as measured by the jump in their students' standardized test scores) have a lasting effect on their students (as measured by students' lifetime earnings, avoidance of teen pregnancy, and college enrollment).  Although the difference between having an average teacher and having an excellent teacher for one year yielded only $4600 in additional lifetime earnings for each student, the cumulative effect is large: A 30-student class would yield $138,000 extra in lifetime earnings as a result of excellent teaching.  (The difference between a poor and an average teacher was quoted as $266,000 in one year of teaching.)  And avoidance of teen pregnancy?  Priceless!  Although admittedly the difference is small (8.1% vs 7.7% chance of teen pregnancy), when it happens to your family it is not a small thing.

I realize that not everything good in life can be quantified, but I think this kind of research is important because good teachers are not paid enough, and this kind of research helps us advocate for them.  (And, one might argue, gives us greater motivation to get rid of poor teachers more quickly.)  Many of us might think from personal experience that the effect of a good teacher is permanent, but previous studies have not supported that conclusion.  Those previous studies looked only at test scores in future years, not these positive long-range life outcomes.  Therefore, this more sophisticated research is an important step forward.

The study addressed fourth through eighth grade, and found that the grade in which a student encountered a good teacher did not matter.  About a year and a half ago, a roughly similar study was conducted for kindergarten teachers, which concluded that good ones brought a $320,000 economic benefit to their students.
You may wish to read the New York Times column addressing the earlier research, and if you wish to dig deeper into the data you can see some slides presented by those researchers.

Update: Nicholas Kristof has written an eye-opening column about this.