When the COVID-19 pandemic hit the U.S. last spring, schools nationwide shut their doors and states cancelled annual standardized tests. Now federal and state policymakers are debating whether to cancel testing again in 2021. One factor they should consider is whether a two-year gap in testing will make it impossible to measure student-level…

Evidence that teachers' short-term instructional effects persist over time and predict substantial long-run impacts on students' lives provides much of the impetus for a wide range of educational reforms focused on identifying and responding to differences in teachers' value-added to student learning. However, relatively little research has…