Granted, all my teaching was before computers, and my approach was "wrong", but I always let guys know that they should take real lessons... Still, you find yourself teaching people a lot over the years, and my main way, beyond basic chord books was to make up blank "fret boards" on clear plastic sheets... Then, when it was time to show scales, I could keep stacking various ones on top of each other to show different pentatonic scales and modes... I have learned a lot since I taught anyone, so my approach would be different, but I think I would still use the plastic sheets...