During the last decades, the role of language in mathematics and mathematics education has increasingly caught the attention of many researchers in the field of education, teaching and linguistics as well. Within this context, a frequent use of the term “Academic Language” (AL) is noticed to label a variety of instances of language. However, today there is no universal or agreed definition for a possible exact meaning of AL in educational research. The present study in mathematics education investigates learners’ discourse competences within different situations of classroom practice, and addresses the following question: How does the use of language and discourse change during different situations in the mathematics classroom?