Recent learning sciences have revealed some of the mechanisms of how people learn through interactions in collaborative educational settings. In this research, we tried to capture the nature of constructive interaction by in-depth qualitative analysis of the discourse in a programming learning environment. The analyzed group was comprised of three female students, all in the sixth grade, who engaged in making an animation using Scratch. However, they had trouble with their object modelling during the task. Through their problem-solving procedure, the students attempted externalizations of their solution ideas, and these interactions promoted their understanding of the problem through the iterative process of each individual. Working collaboratively, the three students used various procedures to solve their shared object-modelling problems.