I like your idea. I've been interested in the use of machine-learning and techniques from AI to improve teaching for a while. It seemed odd to me that no one has been able to effectively apply what we've learned about machine learning to help human learning, despite having computers in the classroom for decades. Creating a system that can learn the optimal strategy to coach a student seems like a pretty well-defined problem. Khan Academy has done some very interesting work in individualized automated teaching methods.