Effective teacher–student interactions are a primary ingredient of high-quality early educational experiences. With the popular CLASS® observational tool, schools can accurately assess classroom quality in K–3 classrooms based on teacher–student interactions rather than the physical environment or a specific curriculum. The CLASS tool This useful manual includes detailed descriptions of the 10 CLASS dimensions, administration procedures, and a technical appendix. One copy of the CLASS® Dimensions Overview, a tri-fold reference sheet for observers, is included with the manual. This user's guide is part of CLASS , the bestselling classroom observational tool that measures interactions between children and teachers—a primary ingredient of high-quality early educational experiences. With versions for infant programs, toddler programs, pre-K (in English and Spanish), and K–3 classrooms, the reliable and valid CLASS tool establishes an accurate picture of the classroom through brief, repeated observation and scoring cycles and effectively pinpoints areas for improvement. Learn more about the entire CLASS system. Sign up for webinars on CLASS presented by Teachstone.