Evidence from a larger project Studying babies and toddlers: Cultural worlds and transitory relationships in Australian long day care settings is gathered. We argue that toddlers co-construct collective knowledge through expressive play activities with peers and educators. We analyse how educators enter play, taking the toddlers’ perspective to develop collective knowledge. We investigate how toddlers creatively produce knowledge through educators’ awareness of their play spaces, aiming to find the different ways they affectively participate in processes of producing knowledge. Vygotsky’s cultural–historical concepts of the social situation of development and play form the research foundation.Using visual narrative methodology and reflective dialogue to explore toddlers’ everyday play activity, one play episode of an educator entering shared collective play with toddlers is analysed. We find educators’ involvement and peer interaction significant for learning and social production of collective knowledge in toddlers’ play spaces. Responding to toddlers’ active expressions by entering play develops collective knowledge.