The purpose of this thesis was to examine teachers’ perception of communication in the Mathematics lesson. I wanted to find out how teachers look at communication as a didactic manner and how they view their role in encouraging communication and discussion during the Mathematics lesson and what communication can contribute to students’ learning in Mathematics, according to their beliefs. I have chosen a qualitative approach; I have interviewed six Mathematics teachers working in three different schools. I assume Vygotsky’s theories of language and learning, Piaget’s theory of accommodation and assimilation and Löwings- and Kilborn’s description of various types of language and communication in the Mathematics lesson.

I have found that a common understanding of the six teachers is that communication between teachers and students as an important factor when the teacher explains new stuff or discusses students’ misunderstanding of a mathematic problem. Communication between students was less important for the teachers. Teachers’ role in creating space for communication was limited, experienced the teachers. They feel that many obstacles that prevent communication during the Mathematics lesson, for example, the traditional approach of teaching Mathematics in schools and the lack of mathematical language of the students.