One crucial question for researchers who study teachers' classroom practice is how to maximize information about what is happening in classrooms while minimizing costs. This report extends prior studies of the reliability of the Instructional Quality Assessment (IQA), a widely used classroom observation toolkit, and offers insight into the often asked question: “What is the number of observations required to reliably measure a teacher's instructional practice using the IQA?” We found that in some situations, as few as three observations are needed to reliably measure a teacher's instructional practice using the IQA. However, that result depends on a variety of other factors.
Anne Garrison Wilhelm, Department of Teaching and Learning, Simmons School of Education and Human Development, Southern Methodist University, P.O. Box 750455, Dallas, TX 75275-0455; email@example.com
Sungyeun Kim, Seoul National University, #611, Education Information Hall (10-1 Dong), 1 Gwanak- ro, Gwanak-gu, Seoul, South Korea 151-742; firstname.lastname@example.org