This observational study examines the classroom dynamics occurring in a collaborative math lab activity in a third-grade classroom. Specific classroom interactions are identified as resources for cultivating children's interest and understanding of mathematical knowledge. Dialogic interchange and physical positioning of teacher and students is explained in terms of promoting interest and understanding. Eisner's evaluation model of Educational Connoisseurship and Criticism is adopted as a means of illustrating the dialogic forces that operate within classroom activity which structure children''s learning and motivation.