This paper deals with one prominent topic in the field of mathematics education: the communication in mathematics. In this article, a framework is proposed for analyzing the effectiveness of communication in mathematics classrooms. The presentation is based on data collected, during a 3-year period, and consists of the students’ tests, the teachers’ lessons plan and reports of the lessons’ instructions. In the analysis, concepts relating to variation theory have been used as analytical tools. The success or failure of communication is a matter of the relation between thought contents of speaker and hearer. The analysis focus on the interaction among the intended, enacted and lived objects of learning. The intended object of learning refers to the part of the content that students should learn and which is supposed to be treated in the classroom. The enacted object of learning is what appears in the classroom and refers to what is possible for students to experience within the learning environment. The students’ initial level of capability to appropriate the object of learning as well as the way in which students understand the object of learning is the lived object of learning. The interaction among the intended, enacted and lived objects of learning is an indication of whether the communication in the classroom is successful or not. The results show that: effective communication occurs in the classroom if it has the real critical aspects in student learning as its starting point; teachers develop new strategies to present the contents by having the focus to open up dimensions of variation.