With the decline in Australian school children's mathematics skills, the spotlight is shining on the quality of early childhood mathematics teaching and learning in the preschool years. Spatial thinking--which includes spatial orientation and spatial visualization--contributes to early mathematical thinking and children have the capacity to demonstrate abstract spatial concepts both verbally and nonverbally, yet may be overlooked in practice. This qualitative study analyses selected excerpts from a corpus of video data of 4- and 5-year-old children participating in a 6-week project designed to support children's spatial thinking skills. A conversation analytic approach is taken to demonstrate children's spatial thinking made visible through gesture and action. Showing how this is done by analyzing the verbal and nonverbal elements of back-and-forth interactions, with explicit attention to the "how" of intentional teaching, reveals the interrelationship between learning and teaching. In addition, the critical role played by in-the-moment formative assessment of children's demonstrated spatial thinking and the maximization of opportunities for teachers to support concept acquisition are emphasized. The analysis of authentic interactions thus serves as a provocation for professional learning.