Turning dilate from point tool into part of an instrument: an example of a preservice mathematics teacher working on a dynamic geometry system

Abstract

International audienceThe aim of this paper is to investigate a preservice mathematics teacher’s instrumental genesis of ‘dilate from point’ tool in a dynamic geometry system. Data is collected through a series of task-based interviews including seven specific construction tasks regarding the use of dilate from point tool with a Turkish preservice mathematics teacher. Video-recorded interviews and screen recorder software productions were triangulated and analysed within the theoretical lens of instrumental genesis. According to the findings, the participant firstly explored the properties of the dilation transformation and its relation to other geometrical concepts and transformations. Secondly, the participant developed instrumented schemes related to the dilate from point tool for applying appropriate strategies in the construction tasks