The Classroom Assessment Scoring System (CLASS)—a systematic observation instrument for the assessment of generic pedagogical teaching characteristics—was transferred to the context of extracurricular sports training. The CLASS follows a hierarchical structure with three domains: Emotional Support, Classroom Organisation and Instructional Support. Each domain comprises three to four dimensions, from which eight seem applicable for the context of sports coaching. To test the suitability of CLASS for sports training, 26 coaches were video-recorded in their training session with children aged approximately 8–12 years. In all, 221 sequences were independently rated by two certified observers in 8 dimensions on a 7-point scale. Confirmatory factor analysis supports a three-factorial structure of the quality dimensions thus confirming the assumed “Teaching Through Interactions Framework”. Moreover, interrater reliability was determined using several measures including Percent Within One (PWO), Cohen’s κ, weighted κ and intraclass correlation (ICC). PWO across the eight dimensions are very good to excellent, ranging from 88–98%. Values for more stringent reliability measures are also acceptable to good, with individual exceptions. ICC consistently reach the statistical significance level (p < 0.01) and range between 0.54 and 0.87. Overall, the results support the transfer of the CLASS to sports contexts.