Present study investigates college students? covariational reasoning in light of five mental actions described in covariation framework introduced by Marilyn P. Carlson. Two high performing college students? reasoning was investigated in a multiple case study design. Analysis of data disclosed that functional situations are conceived as static rather than dynamic. This static approach prevents students from evaluating the whole process as it is happening at once. In other words, students have difficulties to represent continues changes of two variables in a functional situation and coordinate the simultaneous changes of two variables on entire domain. In addition, students? difficulties in graphical representations produce inconsistencies between interpretations and representations of simultaneous changes of two variables. It is also revealed that Students? strong procedural tendency hinders reasoning and meaningful interpretations about change in functional situations.