In this paper, preschool teachers' documentation of their learning about playing as a mathematical activity are examined using Wartofsky's three levels of artefacts, primary , secondary and tertiary. Playing is one of Bishop's six mathematical activities and was a new consideration for most teachers and in contrast to how play is generally conceived as a tool for learning. Wartofsky's three levels of analysis provided insights into how the teachers were able to visualize and understand playing as a mathematical activity.