This critical enquiry into co-construction of meaning in music play uses applied literacy practices to explore children's multimodal interactions. It shows evidence of cultural and social framing of their music making, their forms of organisation and ways of reinventing cultural knowledge during interaction. Using visual methodology and multimodal analysis, this study documents how children in diverse contexts intentionally transmit and redesign prior knowledge. Two case studies of diverse music activities, one in an early childhood rural setting and one in an inner-urban home setting, detail how two five-year-old children expanded communication with each other or with an adult using gestural, audio, spatial and visual modes as semiotic resources. These two multimodal experiences in music play are discussed to demonstrate how, in both situated events, young children demonstrated semiotic import of composing resources to transform prior knowledge in co-operative play. The activities illustrate how music play is a crucial element of everyday learning in early childhood settings. Teachers may promote learning by providing opportunities for children to co-construct and enact literacy in ways that transcend the curricular context. They expand literacy into larger worlds by recognising modes of gesture and spatial relations as students communicate life experiences through music play.