Theorem acquisition and deductive proof have always been core elements in the study and teaching of Euclidean geometry. The introduction of dynamic geometry environments, DGE (e.g., Cabri-Geometre, Geometer's Sketchpad), into classrooms in the past decade has posed a challenge to this praxis. Students can experiment through different dragging…

Recent research demonstrates that many issues related to the structure of natural numbers and the relationship among numbers are not well grasped by students. In this article, we describe a computer-based learning environment called "Number Worlds" that was designed to support the exploration of elementary number theory concepts by…