There was a sign in my 6th grade math classroom that said "You learn..." and then a list of different ways to learn and how much you get out of each.  I liked that poster.  I don't remember much of it, but I remember two stats off that poster:  you learn more by seeing than hearing, and you learn 81% of what you teach to others.
           I find this really intriguing.  Most teachers teach visually, and some hands-on, which is even better -- but when does any teacher have us teach to each other?  
           However, I've seen the poster.  Whenever I study something, I "teach" Mom from my notes.  Usually she already knows the material, but that just means that we teach each other.  Maybe I should teach her math.  Except I don't need much help remembering math stuff.
           So next time you learn something, teach it to someone else.  You'll learn it even better, and they'll learn it too.