Education in this country has evolved dramatically from the days of one teacher in a one-room schoolhouse. Today, student learning is no longer confined to a physical space. Computers and the Internet have broken through school walls, giving students greater opportunities to personalize their education, access distant resources, receive extra help or more-challenging assignments, and engage in learning in new and unique ways. This book provides a new look at the relatively new enterprise of online learning in the K–12 arena, which is expanding rapidly, with increasing numbers of providers offering services and more students choosing to participate. As with any education program, online learning initiatives must be held accountable for results. Thus, it is critical for students and their parents, as well as administrators, policymakers, and funders to have data informing them about program and student outcomes and, if relevant, about how well a particular program compares to traditional education models. Rigorous evaluations are essential to this process and are included in this book. They identify whether programs and online resources are performing as promised, and equally important, they can point to areas for improvement.