At first blush, most folks seem to like the idea of the “Value-added” system of teacher evaluation. It seems intuitively satisfying to think of a system that can rule out the many non-academic issues, school-wide issues, societal issues that children walk into class with like a loaded backpack. With “Value-added” we seem to think we’ve got a system that will isolate the contribution to a students education caused only by her/his teacher. Before choosing to not offer the data, a NYC Education Department spokesperson defended the earlier position by saying that the department, “believes that the Value-added model is an accurate evaluation of teachers.”
“Believe” is a really good word to use. Folks seem to believe in the value-added model because the rhetoric feels so gosh darn solid.
The science of value-added looks a lot different. Just yesterday, the Annenberg Institute released a report detailing the chimera-like realities of the Value-added model.
1. The quality of the teacher is the most significant factor that school’s can control in a child’s education. The quality of the teacher, and all other factors in a school’s control are actually quite small. The research actually points to teacher quality being only 10-20% of a child’s overall education. Family, poverty, and community factors are still more significant.
2. The test scores that the Value-added model is based are highly suspect. Even at their very best, they only measure a tiny sub-set of all of the things we hope children learn in school. Economist Alan Blinder argued in 2009 that the skills vital for success in the labor market in the near future, such as “Creativity, inventiveness, spontaneity, flexibility and interpersonal relations” will be those least amenable to standardized testing.
3. Value-added is grading teachers on a curve. It is, by design, a system that ranks teachers. By design, 50% of all teachers will rank “Average.” By design, another 20% will be labeled “Below Average” and another 20%, “Above Average.” The top 5% will be called, “Excellent,” while the bottom 5% will be labeled “Failures.” It will always look this way, no matter how many “Failures” we fire. There will always be the worst 5%. A district or school’s dream of having all “Excellent” teachers is impossible to achieve.
“The promise that value-added systems can provide such a precise, meaningful, and comprehensive picture is not supported by the data,” concludes the Annenberg report, “Moreover, the set of skills that can be adequately assessed in a manner appropriate for value-added assessments represents a small fraction of the goals our nation has set out for our students and schools.”