Elementary and middle-school teachers are instrumental in determining whether children will go to college, become teen parents, and earn a good salary, a large new Harvard University study has found. The study, which was conducted by a research team of economists, followed 2.5 million students over 20 years and tracked their educational, social, and economic progress, concluding that the higher quality a child's teachers, the healthier and more productive their life path.
On an individual level, the study found the differences in teacher quality to be relatively minor; a single student with a single excellent teacher between grades 4 and 8 is only 0.5 more likely to attend college than a student with an average teacher, and that student would only gain $4,600 in added lifetime income. But on the broader spectrum, researchers say improving teacher quality can make an enormous difference; for example, replacing a poor teacher with an average one could increase the lifetime earnings of a single classroom by $266,000
The study, which the economics professors have presented to colleagues in more than a dozen seminars over the past year and plan to submit to a journal, is the largest look yet at the controversial "value-added ratings," which measure the impact individual teachers have on student test scores. It is likely to influence the roiling national debates about the importance of quality teachers and how best to measure that quality.
Many school districts, including those in Washington and Houston, have begun to use value-added metrics to influence decisions on hiring, pay and even firing.
Supporters argue that such metrics hold teachers accountable and can help improve the educational outcomes of millions of children. Detractors, most notably a number of teachers unions, say that isolating the effect of a given teacher is harder than it seems, and might unfairly penalize some instructors.
Critics particularly point to the high margin of error with many value-added ratings, noting that they tend to bounce around for a given teacher from year to year and class to class. But looking at an individual's value-added score for three or four classes, the researchers found that some consistently outperformed their peers.
"Everybody believes that teacher quality is very, very important," says Eric A. Hanushek, a senior fellow at the Hoover Institution at Stanford and longtime researcher of education policy. "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."
Image: Teacher with students, via Shutterstock.