A good teacher will teach you how to play music before they teach you how to read music.
Think of it; you don't teach a person how to read before they learn how to talk.
The most important function of a teacher, in my opinion, is to maintain a gradual but interesting level of learning, so that the student doesn't move ahead too fast and get discouraged, or too slowly, and get bored and fed up.
I feel lucky to have had lessons (8 years classical, plus the Yamaha Method)) and be able to read music, as well as charts (including the Nashville number system) and it has allowed me much more freedom in where, and how, I use my craft.
You never know where your child will go in the music business, so it's best to have a good foundation.
It's like learning to read and write, and do basic math....it makes things a whole lot easier.
Ian
Edited to add...
You are never too old to learn how to read music, even if you've spent most of your life playing by ear (or by "air" as it used to be called).
I'm teaching a pro piano player (he plays pretty darn good) how to read Fake Book music...he loves it! He'll be 70 the end of this month. He's doing very well, because he has good musical sense to begin with.
[This message has been edited by ianmcnll (edited 11-20-2009).]
_________________________
Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.