Among Steinberg and Garrett’s findings:
• Math teachers were six times more likely to be among the top performers when assigned students who were the highest achievers the previous year. English language arts (ELA) teachers with high achievers in their classroom were twice as likely to be among top performers.
• Only 37 percent of ELA teachers and 18 percent of math teachers assigned the lowest-performing students were highly rated based on classroom observation scores.
• When teachers were assigned a class with higher incoming achievement, they were more likely to see an increase in their measured performance.
• Teachers with higher achieving students are rated higher in “communicating with students” and “engaging students in learning.” These areas reflect teacher interaction with students, so they tend to be student dependent.
• However, measures that depend more on the instructional strategies teachers bring to the classroom — “using questioning techniques” and “assessment to drive instruction” — were largely uncorrelated with student achievement.
Based on their results, Steinberg and Garrett caution that using observation-based measures for high-stakes teacher accountability without understanding and accounting for classroom composition will skew results, with potentially significant consequences.
“The misidentification of teachers’ performance levels has real implications for personnel decisions, and fundamentally calls into question an evaluation system’s ability to effectively and equitably improve, reward, and sanction teachers,” wrote Steinberg and Garrett.
Steinberg and Garrett reviewed data from a previous study that looked at six school districts over two years, including the New York City Department of Education. This Measure of Effective Teaching study randomly matched teachers to classrooms, differentiating between grade and if a teacher is a subject matter generalist or specialist.
The study comes as schools across the country have stepped up efforts to evaluate teachers. By the start of the 2014–2015 school year, 78 percent of states and 85 percent of the largest school districts and the District of Columbia had implemented teacher evaluation reform.