In this study we explored how dramatic enactments of scientific phenomena and concepts mediate children's learning of scientific meanings along material, social, and representational dimensions. These drama activities were part of two integrated science-literacy units, "Matter" and "Forest," which we developed and implemented in six urban primary-school (grades 1st-3rd) classrooms. We examine and discuss the possibilities and challenges that arise as children and teachers engaged in scientific knowing through such experiences. We use Halliday's (1978. "Language as social semiotic: The social interpretation of language and meaning." Baltimore, MD: University Park Press) three metafunctions of communicative activity--ideational, interpersonal, and textual--to map out the place of the multimodal drama genre in elementary urban school science classrooms of young children. As the children talked, moved, gestured, and positioned themselves in space, they constructed and shared meanings with their peers and their teachers as they enacted their roles. Through their bodies they negotiated ambiguity and re-articulated understandings, thus marking this embodied meaning making as a powerful way to engage with science. Furthermore, children's whole bodies became central, explicit tools used to accomplish the goal of representing this imaginary scientific world, as their teachers helped them differentiate it from the real world of the model they were enacting. Their bodies operated on multiple mediated levels: as material objects that moved through space, as social objects that negotiated classroom relationships and rules, and as metaphorical entities that stood for water molecules in different states of matter or for plants, animals, or non-living entities in a forest food web. Children simultaneously negotiated meanings across all of these levels, and in doing so, acted out improvisational drama as they thought and talked science. (Contains 1 table.)