Virtual manipulatives as cognitive tools, dynamic/interactive, Web-based representations and/or technology-based renditions, allow users to engage in mathematical meaning making. This research investigated teacher candidates' perceptions of the mathematical, cognitive, and pedagogical fidelity of Fill and Pour virtual manipulative. Findings suggest that the degree to which the mathematical entity is faithful to the essential mathematical properties of that item in the virtual environment has been granted by teacher candidates to virtual manipulative designers automatically, without closer examining of the mathematical, cognitive, and/or pedagogical fidelity. Further qualitative probing was carried through to better understand the nature of such assumptions. [For the complete proceedings, see ED584443.]