The flipped-classroom approach has gained increasing popularity and interest in engineering education. The purpose of this study was to investigate (a) student perspectives on the flipped-classroom approach in a transportation-engineering course and (b) how students used the in-class time dedicated to collaborative problem solving. To this end, the study adopted a mixed-methods approach. Quantitative data included an end-of-semester survey and student course grades. Qualitative data included information from focus-group interviews with students and video recordings that demonstrated selected groups' problem-solving processes. The results indicated that students found their flipped-classroom experience to be generally positive. Students were shown to engage in five types of behaviors during collaborative problem solving: problem analysis or understanding, individually working on problems, comparing individual work, interacting with peers, and interacting with the instructor.