I took Music Appreciation 101 in college - easiest class ever! All I had to do was listen to a bunch of songs from different artists and genres. It was fun, but it was time consuming (it was also way way before YouTube!).
Now you can get the same thing I got today (for free!) in 4 minutes by watching the following video:
The Evolution of Music, by Pentatonix
For further study:
Pentatonix Does Christmas Carols
They Sold Their Souls for Rock and Roll - Good Fight Ministries (31 videos)
One, Two, Three O'clock, Four O'clock Talk!
