This research is a high-resolution analysis of grade 6 (ages 11-12) children's interview transcripts about the operation of power stations, before and after teaching. The focus of the study was on how children's conceptual development is built at a discursive level, namely how language is used to express changes in their thoughts. The theoretical perspectives of learning pathways and the socio-cultural theory of learning guided the study. Data analysis revealed that children's conceptual understanding can be reflected in changes in their use of words and the meanings associated with them. This was the case even for children who only partially or selectively followed the steps of the introduced learning path. Furthermore, findings indicate that the acquisition of a concept usually precedes the use of the name describing it. (Contains 1 figure and 3 tables.)