This study focuses on the interactions between students, their peers, their teacher, and digital game-based multiple supports provided by a rich learning environment designed in order to promote meaningful mathematics among low-achieving students. Attempting to identify which aspects of the setting facilitated meaningful learning and which were ineffectual or even detrimental to it, the authors traced the knowledge building processes of 11 fifth grade LAS over eight weeks in which they studied subtraction of decimal numbers. Pre- and post-program data were also collected through diagnostic interviews. Microanalysis of lesson transcripts, videotaped computer activities, and individual worksheets revealed differences in tool-use and in interactions among supports, which led to different learning results. The results suggest that digital game-based learning environments may be a key to promote meaningful learning in terms of mathematical strategy building. At the same time, it highlights the complexity of each tool in the environment as well as interactions among tools.