Analyzed two children's use of a computer-based motion detector to make sense of symbolic expressions (Cartesian graphs). Found three themes: (1) tool perspectives, efforts to understand graphical responses to body motion; (2) fusion, emergent ways of talking and behaving that merge symbols and referents; and (3) graphical spaces, when changing…

Presents a case study of how one 11th-grader learned the meaning of the velocity sign. Her learning was not just an acknowledgment of a rule but also a broad questioning and revision of her thinking about graphs and motion. (16 references) (Author/MKR)