Learning science in the middle years can be an emotional experience. In this study, we explored ninth-grade students' discrete emotions expressed during science activities in a 9-week unit on chemistry. Individual student's emotions were analyzed through multiple data sources including classroom videos, interviews, and emotions diaries completed at the end of each lesson. Results from three representative students are presented as cases within a case study. Using a theoretical perspective drawn from theories of emotions founded in sociology, three assertions emerged. First, students experienced frustration when learning new chemistry concepts. Second, frustration was resolved through student-student and teacher-student interactions. Third, frustration was transformed when students were afforded time to revisit new concepts. Furthermore, the teacher's identification of students' emotions enabled differentiation of learning through individualized interactions. Finally, we explain how the temporality of emotions emerged as an important phenomenon and suggest an elaboration to Turner's theorization of emotions.