Every state wants to ensure that its public schools are staffed by excellent teachers, and to this end, most require that teachers complete a state-approved course of study at a school of education before receiving a teaching license. Defenders of these systems of certification (and those who would add to their requirements) contend that studies show that certified teachers are more effective than uncertified teachers, and that research demonstrates links between greater student achievement and teachers with more formal preparation, additional education coursework, and master's degrees.
Kate Walsh of the Abell Foundation in Baltimore was curious about the "100 to 200 studies" that certification advocates cite in support of the notion that taking the coursework required to obtain certification is the best means for preparing teachers. She decided to track down and review every study cited by prominent national advocates of teacher certification (including Linda Darling-Hammond of the National Commission on Teaching and America's Future). Digging through citations with the zeal of an archaeologist, she ultimately located 150 studies going as far back as 1950 that explore the relationship between teachers' educational preparation and student achievement.
When she looked closely at those studies, she found that most of them suffered from deficiencies so grave that no serious researcher would invoke them: conclusions are asserted absent any evidence, basic principles of data analysis are routinely violated (e.g. studies do not control for key variables critical to understanding student performance), studies suffer from serious statistical errors (e.g. aggregation bias), lack of support for certification is disguised behind imprecise or inaccurate evidence, negative findings are overlooked, and less reliable research is cited irresponsibly.
Teacher Certification Reconsidered: Stumbling for Quality, released on October 8 by the Abell Foundation, contains the result of Walsh's analysis of the research on teacher certification. The findings are presented in clear, mostly non-technical language and many examples of flawed research are supplied. The report also includes a table listing studies cited by certification advocates, descriptions of the main finding of each study and why it gets cited, and explanations of the problems found with the study or with claims about it.
Teacher Certification Reconsidered also reviews the findings of studies that investigate the relationship between other teacher attributes (such as verbal ability) and teacher effectiveness, scientifically sound research conducted mostly by economists and other bona fide social scientists. This research suggests that teachers who score higher on tests of verbal ability and those who attended more selective colleges tend to produce higher student achievement, and that secondary school teachers who know more about their subject matter are generally more effective, at least in math and science.
This review of the "evidence" on teacher certification is important for states to consider as they confront the challenge of staffing all of their public schools with qualified teachers. States that hold tight to the notion that individuals must complete a prescribed body of coursework in a school of education before teaching in a public school - a notion that nobody can any longer claim is supported by good research - do so at their own risk.
Teacher Certification Reconsidered: Stumbling for Quality, by Kate Walsh, The Abell Foundation, October 2001.
The National Commission on Teaching and America's Future is expected to post a response to this report on Thursday, October 11, 2001. (A press release announcing the response is already available on their website.)