There is an old adage that many in education have undoubtedly (and unfortunately) encountered at some point in their education careers: that “those who can, do—those who can’t, teach.” For decades now, researchers, including Dr. Thomas Good who is the author of an article published in 2014 in Teachers College Record, have evidenced that, contrary to this belief, teachers can do, and some teachers do better than others. Dr. Good points out in his historical analysis, What Do We Know About How Teachers Influence Student Performance on Standardized Tests: And Why Do We Know so Little About Other Student Outcomes? that teachers matter and that teachers vary in their effects on student achievement. He provides evidence from several decades of scholarly research on teacher effectiveness to show that teachers do make a difference in student achievement as measured by large-scale standardized achievement tests.
Dr. Good is also quick to acknowledge that, despite the reiterated notion that teachers matter and thus should possess (and continue to be trained in) effective teaching qualities (e.g., be well versed in their content knowledge, have strong classroom management skills, hold appropriate expectations, etc.), “fad-driven” education reform policies (e.g., teacher evaluation polices that are based in large part on student achievement growth or teachers’ “value-added”) have gone too far and have actually overvalued the effects of teachers. He explains that simplistic reform efforts, such as Race to the Top and VAM-based teacher evaluation systems, overvalue teacher effects in terms of the actual levels of impact teachers have on student achievement. It has been well documented that teacher effects can only explain, on average, between 10-20% of the variation in student achievement scores (this will be further explored in forthcoming posts). This means that 80-90% of student achievement scores are the result of other factors that are completely outside of the teachers’ control (e.g., poverty, parental support, etc.). Regardless, new teacher evaluation systems that rely so heavily on VAM estimates ignore this very important fact.
Dr. Good also emphasizes that teaching is a complex practice and that by attempting to isolate the variables that make up effective teaching and focusing on each one separately only oversimplifies the complexities of the teaching-achievement relationship. For one thing, VAMs and other popular evaluative practices, such as classroom observations, inhibit one’s ability to recognize the patterns of effective teaching and instead promote a simplistic view of just some of the individual variables that actually matter when thinking about effective teaching. He provides the following example:
Many observational systems call for the demonstration of high expectations. However…expectations can be too high or too low, and the issue is for teachers to demonstrate appropriate expectations. How then does a classroom observer know and code if expectations are appropriate both for individual students and for the class as a whole?
The bottom line is that, like teaching, understanding the impact of teachers on student learning is very complex. Teachers matter, and they should be trained, treated, and valued as such. However, they are one of many factors that impact student learning and achievement over time, and this very critical point cannot be (though currently is) ignored by policy. VAM-based policies, particularly, place an exorbitantly over-estimated value on the impact of teachers on student achievement scores.
Post contributed by Jessica Holloway-Libell
