Background and Context: Physical computing involves complex negotiations of multiple, on and off-screen tasks, which calls for research on how to best structure collaborative work to ensure equitable learning. Objective: We focus on how pairs self-organized their multi-domain tasks in physical computing, and how their social interactions supported or inhibited productive collaboration. Method: We conducted a 30+ hour physical computing workshop where high school student pairs created interactive electronic textile signs. We recorded how students shared or allocated their tasks in fieldnotes and looked for reasons why this occurred through student post-interviews. Findings: Students worked collaboratively on project planning, which involved discussion and decision-making, but individually during project construction, which involved physical execution of their plan. The quality of students' social interaction was seemingly linked to how viewed their partner as a socioemotional resource. Implications: Inherent qualities of the different domains of physical computing and how students view their partners in socioemotional terms can shape the productivity of student collaborative learning.