We aim to understand the impact of scaffolds within a digital workbook to facilitate self-directed learning for learners completing a final project within a community and task-based MOOC. Optional reflection and articulation prompts were embedded in the tool support assignment development. Workbook use was prevalent, with 65% of learners using it to some extent. Our qualitative analysis revealed that assignment responses associated with substantial workbook use were {A) informally written and loosely connected to assignment objectives (36%), or (B) well-articulated and connected to assignment objectives (29%). Responses associated with little to no workbook use were (C) superficial or uncontextualized (29%), or D) consistent with type "B" responses (6%). We discuss implications for instructors and learning designers in scaffolding complex projects in MOOCs.