This chapter reports on a study of students’ learning in the context of mathematics classrooms where the teacher had initiated change in classroom practices. The changed practices included use of cooperative learning strategies and introduction of mathematics tasks that were richer, open ended, and related to everyday experiences of students. Researching students’ learning in the classroom context necessitates taking account of those shared understandings and invisible meanings that establish classroom culture and that provide meaning to the interpretations being made by the participants of the classroom, i.e. the students and the teacher.