The survey data provided insight into students' abilities to correctly identify RCDs, 305 with the data specifically providing insight into the proportion correct and the number of resources that must be activated, and greater RC is needed for the productive application of the resources. For example, for the Markovnikov addition, RC depicts stepwise reactions with intermediates, elementary steps having differing activation energies, and the relationship between the energies of the major and minor products. Likewise, for the Hofmann 310 elimination, the productive application required RC to depict kinetic versus thermodynamic favorability. The survey data is a precursor to the interview data, which explores more closely the specific resources activated for each problem and whether these resources are used productively. Although carbocation resources were activated in several interviews, from Figure , the resources comparing the carbocation stability were generally either not activated or activated and unproductively applied. For mechanistic reasoning, carbocation formation is important; However, comparing two pathways and accounting for the differences is the more important learning outcome that extends beyond rote memory. For assessments, EPFs focus 355 on explaining how a specific product is formed from a given reactant or identifying the major product formed given specific reaction conditions. Therefore, similar to Popova's finding, the focus on the minor product was a challenging task for students during the interview. The resources activated and productively applied focused on the analysis of the major product and not the comparison of the two products.