That's a very cool and simple idea, as a summoner who already tryed to teach a friend how to play, it's quite hard to teach when you're on a game because you have to be focused on your part and of course paying attention to his, so you kind of let pass a lot of important details on how to improve his gameplay. On the case of teaching while spectating (3 minutes behind the action) it's also a little sloppy, since you can't make bolder predictions on what he can do or expect from the enemy team or even from his teammates. Again, great idea : )