This study examines how teachers can structure and use pretend play for teaching science, as well as the impact it has on students' agency, engagement, and discussion. Using interaction analysis, I examine two teachers in two classrooms (n=52) of first and second grade students (6-8 years) at a progressive elementary school. To shed light on how differently play can be structured and integrated into curriculum, I designed two conditions or approaches of inquiry: guided approach and open approach. I argue that while the "guided approach" of inquiry often worked well in learning science concepts, the "open approach" of inquiry sustained student agency and engagement. Findings from the open approach condition also illustrated the impact play had on learning, as well as the importance of designing opportunities for students to experience affect. By understanding the impact affect has on play and learning, this study can inform how to design early elementary science curriculum. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]