Stumbled across this TED Talk whilst browsing for inspiration. Kahn Academy is an online 'coach' that gives students free access to tuition in many subjects - covering most of those subjects in depth, and tracks their progress. The program follows a step process where the learner begins by watching a video explaining the strategy or idea, and follows up with an activity that challenges the learner to practice the strategy as a way of enabling the teacher to devote 100% of his/her time to 'roaming' the class and providing assistance. Something to think about as the digital world becomes more prominent in education.
Website here: https://www.khanacademy.org/