We explored the mediating role of prior knowledge on the relation between intelligence and learning proportional reasoning. What students gain from formal instruction may depend on their intelligence, as well as on prior encounters with proportional concepts. We investigated whether a basic curriculum unit on the concept of density promoted…

The purpose of this paper is to carefully examine the evolution of students' theory building and modeling, critical components of scientific epistemologies, over a unit of study on sinking and floating in one third/fourth grade classroom. The study described in this paper follows in the tradition of Design Experiments (Brown 1992, Collins 1990)…