Design is critical to the successful development of any interactive learning environment (ILE). Moreover, in technology-enhanced learning (TEL) the design process requires input from many diverse areas of expertise. As such, anyone undertaking tool development is required to directly address the design challenge from multiple perspectives. We provide a motivation and rationale for design approaches for learning technologies that draws upon Simon's seminal proposition of design science. We then review the application of design experiments and design patterns and argue that a patterns approach has the potential to address many of the critical challenges faced by learning technologists.