The object of this paper is to present and analyze some observations of the language children in 1st grade (6-7 years old) use when they talk about geometrical objects. The observations are made during a number of encounters with the pupils during one year. The work is part of an ongoing collaboration project between a university college and a primary school. The work can be described as empirical research centered around teaching units where the researcher partly has been a passive observer and partly an active participant in the process. The analysis is based on constructivistic theory and theory about levels of development. (Contains 5 figures.) [For complete proceedings, see ED489597.]