Understanding music theory means knowing the language of music. The main thing to know about music theory is that it is simply a way to explain the music we hear. The concepts and rules that make up music theory are very much like the grammatical rules that govern written language. Being able to transcribe music makes it possible for other musicians to read and play compositions exactly as the composer intended. Learning to read music is almost exactly like learning a new language, to the point where a fluent person can “hear” a musical “conversation” when reading a piece of sheet music.
Music Theory is taught during all lessons but can also be taught with private lessons focusing soley on understanding theory. Theory can be taught to students ages 7+. Preparation for musical theory exams and college prep is available as well. Theory is taught using "Fundamentals of Piano Theory by Keith Snell http://www.methodbooks.com/store/theory/fundamentals-of-piano-theory.htm