This is clearly quite a difficult task -- successfully controlling variables in an educational environment is always going to be difficult. There are so many s

This is clearly quite a difficult task -- successfully controlling variables in an educational environment is always going to be difficult. There are so many students of varying levels, learning styles and parental support structures that it will be a few years before tools like Khan Academy can be fully assessed in a real classroom settings. However, blended learning environments are clearly the future of learning and the only hope for personalizing education in a system that is under constant budgetary pressure with ever increasing class sizes. It will be exciting to see the outcomes of these and future studies. Kudos to Khan Academy for really driving this forward.