Decades of research support integrating play in kindergarten to benefit young students' social, emotional, and cognitive development. As academic readiness becomes a focus, time for play has decreased. As a result, there has been a demand for integration of play with content. This study modifies a project-based science curriculum about how living things grow to include both child-initiated play and teacher-guided play to meet disciplinary learning goals. The curriculum was initially designed to address reform science standards based on knowledge-in-use. We explore how play invites all students to access and understand the phenomenon. The qualitative study involves 18 kindergarteners and their teacher in a Great Lakes state in the U.S. highlighting four lessons during the enactment that emphasized play. Data include observation, audio recording, transcription of interviews, children involved in play, classroom dialogue, and the examination of artifacts. Thematic coding and analysis of field notes, interviews, and dialogue suggest that child-initiated imaginary play and teacher-guided play can promote the science practice, science ideas, and crosscutting concept of patterns needed to explain the phenomenon.