This paper is based on the preparatory study of a doctoral study in which we learned to consider defining in the realm of organizing. In particular, having engaged students in a situation based on "equivalence relations" (from an expert point of view), we report two different ways of organizing the given situation. One of them results in a "new" definition of equivalence relations, and consequently a new representation for them, that seems to be overlooked by the experts. [For complete proceedings, see ED489632.]