Sources of Variance in Principals’ Ratings of Teaching: Baseline and Within-Year Growth Trends

We utilized two years of teacher observation data from a large urban district to examine the timing, sources of variance, and growth of classroom observation ratings by evaluators and teacher self-assessments. Teachers represented the largest source of variance, and the average teachers’ scores experienced modest within-year increases. We found near-zero variance in individual teacher growth, which may reflect homogeneity or data limitations. Findings affirm the potential of classroom ratings to guide decisions about teachers; however, expectations for within-year growth may need adjustment to reflect modest growth rates. Regularly spaced observations, rather than the fall-heavy schedule observed, may better facilitate implementation.