When we invite students to experiment with form, we invite ourselves as instructors to experiment with feedback, criteria, and assessment. We discover the need to own the complexity of multimodal compositions without risking assessment and pedagogical lock-in. Drawing on a conference series design, instructor-student interactions, and sample student work, this article outlines a theory that accounts for the unexpected and promotes rhetorical and emergent assessment in a composition hackerspace. The theory and examples offer writing students and instructors strategies for striking a productive “balance between convention and innovation” (Kuhn, 2008).