Wednesday, July 4, 2012

TL;DR - Teacher Experience Matters

Science, March 2, 2012 -- The Effects of Experience and Attrition for Novice High-School Science and Mathematics Teachers, Gary Henry, C. Kevin Fortner, & Kevin Bastian

There's a lot of things wrong with the public education system in the US, but one of them is its ability to retain high-quality teachers.  Due largely to anemic rates of compensation, a student in public school is likely to encounter either a bright, motivated young teacher -- who disappears in a few years -- or an older teacher who may or may not be that effective.

What does this system mean for students, though?  We already know that teacher quality can play a large role in determining student success, but how much does teaching experience contribute?  If we just look at the number of years that a teacher has been around, we definitely see a positive correlation with student success.  However, is this due to the experience gained by those more senior teachers, or is it just an artifact of less competent teachers dropping out of the profession earlier?

Henry, Fortner, and Bastian attempted to address this question in a large-scale retrospective study looking at teachers in North Carolina.  Their sample included end-of-year test scores for hundreds of thousands of students, linked with thousands of teachers across several math and science (STEM) courses, as well as several non-STEM courses.  In the analysis, they were able to separate and compare the teachers who would and would not continue teaching after five years.

One thing they found was that teachers who remained past five years were more effective than teachers who dropped out earlier, supporting the hypothesis that lower-quality teachers leave the profession earlier.  But they also found a clear upward trend over the years for the other teachers; over the course of five years, the test scores for the teachers' classes increased reliably.  Experience does matter.

But all experience is not equal.  While there was a general upward trend for all teachers, physics and chemistry teachers demonstrated the greatest increase.  How about those non-STEM teachers?  They actually showed much smaller gains in efficacy over the years, essentially leveling out by year 3.  It should be pointed out that this doesn't mean the non-STEM teachers were any worse (or better) than the STEM teachers.  Comparing physics scores to English scores is one of those apples/oranges situations.  So it's not clear why there was this difference across disciplines.  Is there something about STEM courses that makes hands-on experience more valuable than for non-STEM courses?  Or is there something about the teacher training that the teachers receive?  Unfortunately, we can't really tell from this study.

Regardless, it's clear that the sort of rapid turnover that we're seeing in public schools is doing a big disservice to our students.

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