The maintaining dragging scheme and the notion of instrumented abduction

Research has shown that the tools provided by dynamic geometry systems (DGSs) impact students’ approach to investigating open problems in Euclidean geometry. This paper presents results from a study on how a particular dragging modality, maintaining dragging (MD), can be used for generating conjectures in open problem situations. The study served to test and refine a model describing a utilization scheme (the MDS) associated with MD. In particular the paper discusses the abductive nature of the MDS leading to the new notion of instrumented abduction. Moreover the paper provides evidence that solvers can “free” the MDS from the physical dragging-support, developing a powerful psychological tool.