As learning technologies proliferate, it is important for research to address how to best align instruction to educational goals. For example, recent evidence indicates that working collaboratively may have unique benefits for facilitating the acquisition of conceptual understanding, as opposed to procedural fluency (Mullins, Rummel & Spada, 2011). To investigate this effect, we leverage and expand upon a new methodology, dual eye-tracking, to understand how collaborators' joint attention may impact learning in a collaboration-enabled Intelligent Tutoring System for fractions. We present results from a study in which 28 pairs of 4th and 5th grade students completed a set of either conceptually-or procedurally-oriented instructional activities in a school setting. Results indicate that students collaborating exhibited learning gains for conceptual knowledge, but not for procedural knowledge, and that more joint attention was related to learning gains. These results may inform the design of future learning technologies, and illustrate the utility of using dual eye-tracking to study collaboration.