Complex sentence: Stewart's uncle gave him a flute as a birthday gift, and his mother bought a flute method book; he then began to teach himself to read music from this book at 11 years of age.
Split into simpler sentences: Stewart's uncle gave him a flute as a birthday gift, and his mother bought a flute method book for Stewart's new toy. He then began to teach himself to read music from this book at 11 years of age.