The answer lies in DVD University courses and online courses many grades ahead of him. I shall put in some of his favorite on line courses. I highly recommend that you research on your own....however, I have given you a very good starting point. Some courses are simply too expensive and do not offer anything more than the ones my wife has chosen for him. What Alex responds to is also indicative of his learning style....so it may not fit all. I do encourage you to check these out first though. They were chosen after seeing the depth of explanation and the resulting understanding that Alex had with them.
I have NO ulterior motives here. I get no money from this Blog or from the links I incorporate within. I do this purposely so the information may remain pure...simply the best results, done within economically reasonable bounds, and in the most efficient manner..what else matters?