This case study used a design-based research approach to examine the development and evaluation of an online homework system to support learning and problem-solving in a high school physics course. Emergent themes included challenges of building the system, strengths and weaknesses of it, and the benefits to students. While the system largely met desired outcomes and was well received by the students, concerns were raised about the quality and timeliness of some feedback/scaffolding provided by the system. Development of other such systems may help to support students and teachers during the current and post-COVID educational transition.