The aim of the study is to map patterns of teaching quality through interactions in Mathematics lessons in lower secondary school classrooms. The sample is 10 ninth-grade classrooms in Norway (pupils' age, 14-15 years). Reciprocal linkages between teaching through interactions in Mathematic lessons and pupils' results on a standardized National Curriculum Mathematic Test, before and after observed lessons (N = 115) over 7 months, are studied. To map quality of teacher-pupil interactions in classrooms, observations are video recorded and analyzed using Classroom Assessment Scoring System. Video analyses elicit that there is a variety in teacher-pupil interaction quality in the 10 classrooms concerning "emotional support," "classroom organization," and "instructional support." The lowest quality is found for the dimensions "analysis and inquiry," "instructional dialogue," and "regard for adolescent perspectives," which might preclude facilitation of cognitive and metacognitive strategies to enhance pupils' learning and engagement in work with instructional content. Highest quality in teaching through interactions is found for the dimensions "behaviour management" and "productivity." Analyses show that "positive climate" and "student engagement" both have strong effect sizes and are significant concerning pupils' learning on class level when comparing classrooms with the highest and lowest improvement score on the standardized National Curriculum Math test over 7 months.