Merrill (2002a) created a set of fundamental principles of instruction that can lead to effective, efficient, and engaging (e[superscript 3]) instruction. The First Principles of Instruction (Merrill, 2002a) are a prescriptive set of interrelated instructional design practices that consist of activating prior knowledge, using specific portrayals to demonstrate component skills, application of newly acquired knowledge and skills, and integrating the new knowledge and skills into the learner's world. The central underlying principle is contextualizing instruction based on real-world tasks. Merrill (in press) hypothesizes that if one or more of the First Principles are not implemented, then a diminution of learning and performance will occur. There are only a few studies that indicate the efficaciousness of the First Principles of Instruction. However, most claims of efficacy in the application and usage of the principles are anecdotal and empirically unsubstantiated. This phenomenon is not isolated to the First Principles of Instruction. Claims of effectiveness made by ISD model users have taken precedence over empirically validating ISD models. This phenomenon can be attributed to a lack of comprehensive model validation procedures as well as time restraints and other limited resources (Richey, 2005). Richey (2005) posits that theorists and model developers tend to postulate the validity of a model due to its logicality and being supported by literature, as is the case with the First Principles of Instruction. Likewise, designers tend to equate the validity of a model with an appropriate fit within their environment; that is, if using the model is easy, addresses client needs, supports workplace restraints, and the resulting product satisfies the client then the model is viewed as being valid (Gustafson & Branch, 2002; Richey, 2005). Richey and Klein (2007) emphasis the importance of conducting design and development research in order to validate the use of instructional design models, which includes the fundamental principles (e.g., First Principles of Instruction) that underlie instructional design models. These principles and models require research that is rigorous and assesses the model's applicability instead of relying on unsubstantiated testimonials of usefulness and effectiveness (Gustafson & Branch, 2002). In order to validate the use of principles and models researchers need to explore and describe the usage of the principles and models to determine the degree of implementation in different settings (Richey & Klein, 2007). The purpose of this study was to examine the use of the First Principles of Instruction (Merrill, 2002a) and the decisions made by instructional designers -- including project leads, team leads, and designers-by-assignment. The investigation of the use of the First Principles was part of an effort to determine if these principles were conducive to being implemented during a fast-paced project that required the design and development of a large number of online modules. The predominant research question for this study was: How were the First Principles of Instruction used by instructional designers, in a short-term, high volume, rapid production of online K-12 teacher professional development modules? Four supporting questions were also addressed: 1) What were the conditions under which the First Principles of Instruction were used? 2) What design decisions were made during the project? 3) What is the level of understanding of the First Principles by instructional designers? 4) How frequently do the modules incorporate the First Principles of Instruction? This case study involved 15 participants who were all instructional designers and designers-by-assignment that worked on 49 science and math professional development modules for K-12 teachers within a short 11-week time period. Participant interviews, extant data--project management documents, e-mail communications, personal observations, recordings of meetings, participant surveys, and the evaluation of nine online modules consisted of the data collected in this design and development research study. The results indicated the First Principles of Instruction were not used at the level expected by the lead designer and may not be conducive to being applied as described by Merrill (2002a, 2007a, 2009a, 2009b) in this case. The frequency of use of the First Principles in the modules showed an overuse of the "Activation/Tell" principle in relationship to the number of "Demonstrations/Show" and "Application/Ask applications". Results also indicated that the project requirements, personnel, designer experience, the physical setting, and training and meetings contributed to decision-making and ultimately to the use and misuse of the First Principles of Instruction. [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/en-US/products/dissertations/individuals.shtml.]