A project is a finite activity aimed at producing a tangible product or service. Designing and developing instruction is a type of "project." Instructional design projects ("design projects") require instructional designers (IDs) to manage multiple and often overlapping work tasks, balance the "triple constraint" (time, budget, and quality), and react to project changes. Thus, "project management" (PM) is a critical aspect of instructional designer competencies. Traditionally, professional development (PD) involves the use of "cases" that present a complex, realistic problem for learners to discuss. Most of these cases are "static"; the problem does not change during the learning process. Static cases do not engage learners in anticipating and resolving project changes, including client requests for scope additions, or changes in budget or timelines; therefore, novice IDs and project managers (PMs) are often ill-prepared to work on real-world, complex, dynamic projects.PD should engage learners in "thought and action" around "messy" project problems. "Zingers," realistic and unexpected challenges, were introduced while graduate students were developing a PM plan for a design project. These zingers were designed to simulate the complex, dynamic real-world practice of PM within instructional design (ID) work. This dissertation study aimed to inform the design of instruction to develop the expert-like thinking strategies and practice strategies required to respond to unexpected events and solve messy problems. The "case study research method" (CSRM) was used to "describe" the learning process during the "progressive case" by tracking participants' flexible thinking (cognitive flexibility [CF]) and PM judgment in "thought" and "action dimensions" over a semester. In general, the selected teams approached the zingers differently. In most cases, teams made optimistic assumptions, did not balance constraints, and submitted PM plans with internal inconsistencies. While teams had difficulty executing responses to unexpected changes on their PM plans, they exhibited flexible thinking and an understanding of PM concepts in their reflections and discussions. Thus, participants demonstrated more CF than PM judgment, and their "thoughts" exhibited more CF and PM judgment than their "actions." [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]