The purpose of the study is to investigate how teachers for grades 4 and 6 introduce geometric concepts based on Van Hiele´s levels for understanding geometry. The purpose of the study is also to investigate pupils´ use of geometric concepts in conversations based on central concepts in geometry teaching. The purpose is broken down with the following issues:

• Which of Van Hiele´s levels can be identified when introducing geometric concepts?

• How do pupils use geometric concepts in conversations during the introduction?

These are explored through observations that are supplemented with interviews. The data collection will be based on an interview guide and an observation schedule. This study is based on the theories of Van Hiele´s different levels of understanding geometry and central geometric concepts in teaching. There will also be Vygotsky´s sociocultural perspective regarding the nearest development zone for possible dialogue between scientific- and everyday concepts. The result shows that teacher 1 uses visualization, while teacher 2 and 3 use visualization and analysis to introduce geometric concepts to the pupils. Teacher 1 uses images and explanations and combines these with concrete material, while teacher 2 and 3 use laboratory exercises to promote pupils’ analytical skills. The mathematical language is linked to the pupils´ well-known phenomenon in the teaching of teacher 2 and 3, but not teacher 1. It shows that the teaching of geometry of teacher 2 and 3 is permeated by linguistic support to reach the interaction and to understand the meaning of the geometric concepts.