Merrill's first principles of instruction (FPI) are considered as fundamental principles for improving instructional effectiveness regardless of context, approach, or audience. However, very little research explores in detail the process of implementing FPI in course design. In this case study, we provide specific descriptions of how we applied Merrill's FPI in an online course redesign project. Using the rapid prototyping approach, we analyzed the needs of the redesign project, developed the project objectives and plans, and conducted a parallel processes of design, development, and implementation of the new course features. Thirteen redesign tasks were identified, prioritized, and completed to enhance the application of FPI. Students indicated in the course evaluation forms that the redesigned course presented the connections between theories and practice more effectively. We discus this study's implications for the application of FPI and the rapid prototyping model and make suggestions for future research.