Interest in geology topics does not necessarily occur spontaneously, particularly for students in introductory geology classes. If students' level of interest in geology topics increases, they can also experience an increase in their learning, motivation, engagement, and success in class. This is particularly important for first generation and underrepresented students. Instructors can foster student interest in geology topics using a variety of teaching strategies. We developed a short instructional intervention to promote student interest in introductory geology labs and conducted a mixed methods study to examine how student interest developed. The intervention was one of six affective domain interventions developed as part of a larger project. The interest intervention was created to be a two-part flipped teaching strategy. First, students learned about interest and how it affects their learning in an online prelab. As part of the prelab, students read about interest, learned strategies for increasing their interest, and completed a low-stakes assessment of their learning. Next, during the first 10 minutes of their geology lab, students practiced the strategies for increasing their interest. This practice had them write short narrative stories describing their interest in geology topics and connecting the geology class to their academic goals. We collected pre and post survey data to measure their change in interest levels. We also analyzed their narrative stories. We describe the types of topics students were interested in, what role they see the introductory geoscience class having in their larger academic goals, and how their interest changed over time.