The aim of this article is to examine the role of children’s awareness of the function of language use in expressing understanding. Preschool and elementary school children were asked two questions presenting a problem that could be described in classical mechanics and basic astronomy. They were then encouraged to reflect on their own language use when expressing their conceptions of the physical phenomena they had discussed. The article concerns learning from a phenomenographic perspective, with emphasis on the interplay between language use and meaning-making when developing understanding. Understanding is seen as an activity, while awareness of language use in understanding is regarded as an important aspect. 40 children in preschool and elementary school (six and ten years old respectively) participated in an empirical, qualitative investigation. A particular dialogue format was used, that has been developed within the intentional-expressive approach. Dialogue excerpts where the children expressed awareness of their own language and understanding were selected from the empirical material, and contextual analysis was used to delimit qualities of awareness expressed in these excerpts. The qualities of awareness were grouped in four descriptive categories: 1) awareness of the relation between language form and language meaning; 2) awareness of the nature of understanding; 3) awareness of the expressive function of language for new meaning; and 4) awareness of the function of language use in understanding. A widened definition of language awareness is proposed and discussed, in which awareness of the close relationship between language use and meaning-making is taken into consideration.