This document discusses the development and challenges of K-12 online learning. It examines the history of K-12 distance education and online learning. It outlines three roles for virtual school teachers: designer, teacher, and site facilitator. It reviews research related to each role and discusses areas for future research, such as effective web-based design and teaching strategies for online learning. The document proposes using design-based research and evaluations from programs like the Virtual High School Global Consortium to help address challenges in determining if online learning can meet the needs of all K-12 students.