The goal of this paper is to illustrate different ways that cardsorting activities (or "card stacks") can be implemented in the introductory physics classroom, along with various tips and resources for getting started. My first attempt at developing a card stack came about from simply wanting to try out a fun way to change student groups. With 24 students in one of my classes, I made cards for six different situations of constant velocity (each with four different representations as shown in Fig. 1). At the start of class, students were given a single card and asked to find their matches. Chaos ensued as students began, but this was soon followed by lots of productive talk among students about who was and was not a match and why. After things settled down, students were asked to draw the velocity vs. time graph for their situation and to then see if any other groups had drawn the exact same graph. Upon finding that another group did, they were asked, "Why are you a match now, but not before?"