This study investigated college students knowledge of functions before and after instruction using the Rule of Three. The Rule of Three is the dictum that functions should be taught symbolically, graphically and numerically, and as many examples as possible should combine all three views. OCallaghan (1998) and Markovits, Eylon, and Bruckheimers (1986) frameworks for examining components of the concept of function were used to investigate the students knowledge. Four students were chosen based on pretest scores, written responses, and scheduling conflicts. Data were collected from translating...