This research investigates the social learning affordances of a room-sized, immersive, and interactive augmented reality simulation environment designed to support children's understanding of basic physics concepts in a science center. Conversations between 97 parent-child pairs were analyzed in relation to categories of talk through which children's activities are structured, and their physical and perceptual experiences are related to scientific content knowledge. We provide a detailed account of how parents guide children's scientific reasoning in this novel learning environment, such as by structuring the exploration, and emphasizing perceptual observations as evidence and data. We argue that this particular type of interactive environment affords activities that support learning of complex ideas in science, empowering parents to provide support to the children's perceptual focus and physical engagement. Our findings contrast with studies on high-interactive immersive environments that have typically shown that children tend to isolate themselves from their social surroundings. Mixed-reality environments, in contrast, appear to support significant social interaction, while still offering children playful and engaging experiences.