Conversation Analysis uncovers features of talk-in-interaction during "real life" conversations. When these phenomena are repeatedly observed in the data, conclusions can be drawn regarding the function of the phenomena as elements of talk. In this project, we drew on a corpus of video-recordings collected in five different early childhood education and care settings in Melbourne. We were interested in pinpointing precisely "how" feedback that expands learning and encourages sustained engagement was enacted by teachers during play-based mathematics activities. This fine-grained focus provides research-based evidence to support teachers using these strategies in a purposeful manner as an element of intentional teaching. Although this case study draws on data gathered in an early childhood setting, readers are encouraged to reflect on the application of conversation analysis as a methodology and method to data gathered in diverse contexts. [This content is provided in the format of an e-book.]