[Editor’s note: This story, originally published on January 19th of this year, was our #3 most popular story of the year. The countdown continues tomorrow with #2, so be sure to check back!]

Teachers might be at a disadvantage during classroom observation of their instructional practice, which is one of the most widely-used tools for high-stakes job performance evaluations. And whether or not students have a history of high classroom achievement could be the reason why.

Research from the University of Pennsylvania Graduate School of Education (Penn GSE) and the American Institutes for Research (AIR) indicates that evaluations based on observing teachers in the classroom often fail to meaningfully assess teacher performance.

The study, published in Educational Evaluation and Policy Analysis, adds to the ongoing policy debate over when and how teachers should be evaluated.

Researchers Matthew Steinberg, from Penn GSE, and Rachel Garrett, from AIR, found that students’ prior academic achievement is a significant predictor of teacher success in the high-stakes evaluation system.

“When information about teacher performance does not reflect a teacher’s practice, but rather the students to whom the teacher is assigned, such systems are at risk of misidentifying and mislabeling teacher performance,” Steinberg and Garrett wrote.

(Next page: Which teachers are more likely to be among top performers when assigned high-achieving students?)