Middle school students are faced with a number of mathematical concepts that require new forms of reasoning. Although the shifts toward proportional and algebraic reasoning are often emphasized in middle school curricula, changes in the nature of geometric reasoning are not always given the same weight. As highlighted in "Catalyzing Change in High School Mathematics: Initiating Critical Conversations" (NCTM 2018), transformations have taken a more prominent role in secondary geometry instruction, a dramatic change in the way geometry has been previously taught (Thomas and Edson 2015). Moreover, transformations are often not adequately represented in traditional U.S. curriculum materials (Usiskin 2014), and many teachers may not be fluent with these ideas (Seago et al. 2013). From a mathematical standpoint, the study of transformations is an important gateway to such concepts as function, ratio and proportions, symmetry, similarity, and congruence. Traditionally, congruence is introduced to students through the informal notion that two congruent figures are the same size and the same shape. Although this notion of congruence works at an intuitive level, a dramatic disconnect occurs between this informal way of thinking and how congruence is traditionally taught at the high school level, where congruence is typically based on triangle congruence criteria.