On The Importance of Good Teachers

I have long been a proponent of the "smaller class size" school of thought for improving student performance. It just seemed logical to me that if there were fewer students per teacher, each student would get more of the teacher's time, and would then benefit from a better education. One of the great things about No Child Left Behind (and I believe it has its pretty sizeable flaws) is the requirements for data gathering and analysis about schools that it imposes. This data analysis can put hypotheses like "smaller class sizes" to the test.

Some data is starting show that the most basic element of student performance is the teachers themselves. Not class size, not funding, not curriculum. Teachers.

The testing mandates in No Child Left Behind had generated a sea of data, and researchers were now able to parse student achievement in ways they never had before. A new generation of economists devised statistical methods to measure the “value added” to a student’s performance by almost every factor imaginable: class size versus per-pupil funding versus curriculum. When researchers ran the numbers in dozens of different studies, every factor under a school’s control produced just a tiny impact, except for one: which teacher the student had been assigned to. Some teachers could regularly lift their students’ test scores above the average for children of the same race, class and ability level. Others’ students left with below-average results year after year. William Sanders, a statistician studying Tennessee teachers with a colleague, found that a student with a weak teacher for three straight years would score, on average, 50 percentile points behind a similar student with a strong teacher for those years. Teachers working in the same building, teaching the same grade, produced very different outcomes. And the gaps were huge. Eric Hanushek, a Stanford economist, found that while the top 5 percent of teachers were able to impart a year and a half’s worth of learning to students in one school year, as judged by standardized tests, the weakest 5 percent advanced their students only half a year of material each year. - The New York Times

Of course, at this point it is important to remember the words of a good friend who is a teacher in Fairfax. "I don't think you can objectively measure a teacher's effectiveness through student grades and test scores because there are so many other variables at play (namely, the students themselves)."

Nonetheless, it is nice that our debates over school and education policy are becoming more informed by rigorously gathered and analyzed data, even if it verifies some obvious conclusions like "teachers matter."

[Update] Nicholas at Donkeylicious weighs in on the subject as well.

[Update] New nationwide academic standards for public schools?