While teacher evaluations haven’t garnered as much media attention as the Common Core, in the education world it has been nearly as controversial. And just like the Common Core there are a number of myths about teacher evaluations that impede important discussions on how evaluations can best be used to improve student performance. Even this insightful EdWeek essay by a Philadelphia high school math teacher included some popular myths such as:
Value-added systems provide precise percentile rankings of teachers
While value-added models certainly can provide percentile rankings of teachers this is typically not the case. The objective of most value-added measures is not to create rankings—which wouldn’t be very precise—but to determine if a teacher is more or less effective than an average teacher. Value-added measures cannot, should not, and typically are not used to rank teachers from best to worst in any teacher evaluation system.
The impact of a given teacher on student performance is too small to accurately quantify
Because there are a number of factors besides teachers that impact students’ test scores, this is exactly the reason why value-added measures should be used. It is the only quantifiable measure that even attempts to isolate the impact of the teacher from other factors that influence student achievement. As this video shows, teachers have a tremendous impact on the academic success of their students.
The differences between schools are too great to accurately quantify
It is true that large differences between schools have an impact on teacher effectiveness which is why high quality value-added models are designed to minimize the impact of such differences. A good value-added model will compare teachers within the same school or similar schools to control for the differences between schools. These controls are not perfect but they provide a more accurate assessment of how a teacher would perform in a typical school.
Teachers are blindly fired due to flawed data that doesn’t provide context
While the other three myths had some nuggets of truth, this one is totally untrue. As I found in my Trends in Teacher Evaluation report, no state relies solely on value-added (or any one measure of student achievement) for more than half of a teacher’s overall evaluation. Even in states where half of a teacher’s evaluation is based on measures of student achievement, most of these states require that multiple measures of student achievement be used, such as student learning objectives, formative assessments and teacher developed exams.
Furthermore, in just about every state evaluation system, the lowest-performing teachers are provided additional professional development, mentoring, or other assistance to help improve their performance. Only if the teacher fails to improve after multiple years of low performance do they become eligible to be fired. And in most states the district still has the final say on whether a teacher is fired or not. So while teacher evaluation systems are used to identify low-performing teachers, it is still up to district leaders in most states to determine what to do with that information. – Jim Hull