As far as I am aware Instruction allows you to teach equal to your level in anything that you have at the same level as your instruction.(Academics 3 +Instruction 3 can teach Academics 3 while Academics 3 Instruction 2 could still only teach Academics 2.)
This ability is -usually- required to teach more than one person at a time, like in a classroom setting, with the usual 1 under your current level requirement applying there. We tend to have 'classes' without limiting ourselves to possession of this ability, so that isn't really an advantage for our game.