Dragging, instrumented abduction and evidence, in processes of conjecture generation in a dynamic geometry environment

In a dynamic geometry environment (DGE) conjectures can be generated by manipulating figures with different dragging strategies. One strategy (maintaining dragging) that has been the focus of various studies, consists of inducing a specific geometric property and trying to maintain it. In this paper I focus on abduction and evidence within such processes of the generation of conjectures. I discuss the particular nature of the abductive process associated with the use of maintaining dragging (instrumented abduction). In respect of other forms of abduction reported in the literature, I highlight their key role in bridging phenomenological evidence and theoretical evidence. Results from analysis of a case study suggest that using maintaining dragging leads students to the generation of conjectures with solid phenomenological evidence. On the other hand, the process withholds a potential fragility with respect to proof of the conjectures generated, due to the scarce theoretical evidence stemming from it.