As noted above, among the characteristics of successful mathematics problem solvers is their ability to create and
use appropriate representations, both internal and external. The notion of representation has been used in different but
interrelated ways by researchers (Putnam, Lampert, & Peterson, 1990). For this study, we were interested in external
pedagogical and solution representations; that is, the material forms used by teachers to express abstract mathematical
ideas. (See Goldin, 2002, 2003, for extended discussions of internal and external representations.)