Sustainability education is increasingly understood as necessary for young children. An important aspect of early childhood sustainability education is associated with how best to integrate the conceptual basis of sustainability education with existing play-based pedagogies. Play-based pedagogies can be understood as occurring along a continuum, including more open-ended and freely chosen play to more teacher orientated play-based activities. Each of these play types suggests different opportunities for teacher's engagement with children's learning. This paper examines how three different types of play-based pedagogy, including open-ended, modelled and purposefully framed play, prompt teacher planning for children's learning about biodiversity as a knowledge subset of sustainability education. Vygotsky's description of combinatorial activity is used to consider the extent to which each play type prompts teachers to plan for children's engagement with biodiversity concepts in ways that are most likely to support knowledge construction. (author abstract)