This design case details a seven-year iterative design process to create an app for use in online physical education classes. Each iteration addresses the shortcomings of the previous version. The most recent iteration of the app allows students to use Fitbit™ devices to record heart rate data, which each student sees as progress toward course goals on the homepage of the course. The current version of the app has evolved to provide a seamless student experience using a web application programming interface (API) and data standards such as learning tools interoperability (LTI). The student experience of using the app is thoroughly documented, as are design processes and principles for engaging in similar design processes.