Background: Literature contends that a teacher's knowledge of concept map-based tasks influence how their students perceive the task and execute the creation of acceptable concept maps. Teachers who are skilled concept mappers are able to (1) understand and apply the operational terms to construct a hierarchical/non-hierarchical concept map; (2) identify the legitimacy of the constructed concept map by verifying its graphical structure and its educational utility; and (3) determine the inherent "good" and "poor" qualities of the resulting graphical structure to reiterate the "good" qualities and to coach and provide feedback to alleviate "poor" qualities. Purpose: The purpose of this study was to investigate the nature of prospective teachers' knowledge underpinning the technique used to construct concept maps and thus, explicate their facility to construct concept maps. Sample, Design and Methods: Data consisted of 200 concept maps constructed by prospective teachers in an elementary science methods course. Results: Analysis revealed that the prospective teachers had predominantly constructed either hierarchical and/or non-hierarchical concept maps. It is likely that their maps reflect the teaching that they themselves would have experienced in their science classrooms during their own education. Additionally, most of these concepts maps only contained the root concept and subordinate concepts and lacked directional linking lines, linking phrases, labelled lines and propositions. Conclusions: We argue that teacher educators need to assess their prospective teachers' understanding of concept mapping in relation to the legitimacy (the nature and quality) of the end-products (graphical structures) of such practices. Prospective teachers also need to understand the educational utility of concept mapping in terms of how these end-products impact and/or effectuate learning.