How Much Do Teachers Matter?

Earlier this month, economists at Columbia and Harvard released the findings from a study that followed 2.5 million students from third through eighth grade well into adulthood. Their key finding? Time spent with a good teacher has wide-ranging positive effects for the rest of a kid’s life.

Because the researchers followed the same students for 20 years, they could link performance in elementary school to later life outcomes. Instead of looking at how a teacher did in her classroom from one year to the next, they used their vast data sets to track each kid’s performance. In this way, they could more accurately judge whether a particular teacher consistently helped kids learn.

Then, they took the long view. They looked at what was going on with those kids two decades later. That’s where the true importance of good teachers comes in. In every aspect, the students who had strong teachers capable of consistently boosting test scores also had measurably better lives years later.

According to Slate:

“Students who had high value-added teachers in grade school attended college at higher rates (and attended better colleges), were less likely to be teenage mothers, and earned more in early adulthood.”

The data came from 2.5 million students from a large urban school district from 1989-2009. The researchers could see in black and white the effect of a school hiring a high value-added teacher (big boost in student performance) as well as the drop in performance at the school that teacher had left.

In The New York Times article that first reported these findings, Eric Hanushek, a senior fellow at the Hoover Institution at Stanford and longtime researcher of education policy, says:

“Everybody believes that teacher quality is very, very important. What this paper and other work has shown is that it’s probably more important than people think. That the variations or differences between really good and really bad teachers have lifelong impacts on children.”

Years ago, I made my own short-lived foray into the world of teaching high school English. It was as simultaneously hard and rewarding as everyone says it is. But before I stepped foot into a classroom, I recall being frustrated by the lack of solid information on what to do and what not to do. As a new teacher, I wanted tried-and-true techniques and was told to experiment because each student was different and I would have to adjust accordingly. While I see the truth in that, I also believe my students suffered in my inexperienced care.

One thing this new study shows is the importance of measurement, and the truth that there are tried-and-true techniques that work time and again for the best teachers. At the end of the day, using the data we have on hand proves what we all thought we knew — good teachers matter — but couldn’t be sure.