Thin slices of teaching behavior: Video observation as complement to the assessment of teaching quality and teacher training interventions

In research on teaching and teachers, there is a need for valid and economic methods of assessing teaching quality. One approach to such assessment of teaching quality is the so-called thin slices method of video observations—short sequences judged by briefly trained raters. Until now, this method has been used on cross-sectional data only, and not in studies evaluating professional development programs of teachers. In this study, ratings of 41 teacher trainees were cross-validated with student judgments ( N = 806) of the same observed lessons in the context of a mindfulness intervention study. For the aspects Disturbances , Time Efficiency , and Student Support , the agreement of students’ and external raters’ ratings was established, underscoring the criterion validity. Additionally, ratings based on the thin slices method were sensitive enough to detect general time effects during teacher training and training effects of an intervention for teachers both on classroom disturbances. • Thin slices is an economical, reliable way to assess certain teaching quality aspects • Students’ and thin slices ratings on teaching agree more on low-inferential aspects • Assessment method detects intervention effects regarding disturbances in class