"Dimensions of possible variation" is a phrase that now occupies a safe place in the literature describing the application of education theory to education practice: "asking yourself what could be changed [in the task], while using the same approach or technique, opens up dimensions of possible variation. A set of exercises forming a sequence of tasks for learners to work through piecemeal [is transformed] into a domain of generality--a technique in the full sense of the word (Mason and Johnston-Wilder, 2004)." In this article, the author shows how dimensions of possible variation can turn a routine problem into something much more interesting, and describes how this idea genuinely helped his ability to convert theory to practice. (Contains 1 figure.)