Here are resources for learning more about the history music.
Resources for Students in Books 1-3
Video: Origins of Music – The Story of Guido (4 mins)
Classics for Kids: Musical Eras
Classics for Kids: Interactive Composer Timeline
Classics for Kids: Women Composers
Music by Black Composers (new coloring book!)
Violin and Viola Music by Women
Resources for Books 3-4 and Beyond
Wikipedia: Classical Music Page
ClassicFM: Composers : Start Here for Composer Biographies
Violin and Viola Music by Women
ClassicFM: The Great Women Composers