This study sought to replicate previous work in student conceptions of formal proofs based on informal arguments, originally explored by Zazkis et al. (2016). Additional tasks were added to the experiment to produce new data that could further verify the analysis of Zazkis et al. (2016) as well as provide more insight into how students comprehend proofs, what types of mistakes occur, and why. Results from one-on-one interviews confirmed that some students were not able to make accurate informal to formal comparisons because they were not considering multiple facets of the problem. Additionally, patterns in the students’ analysis introduced more questions concerning the motivations behind what students choose to think about when they read and dissect proofs.