The evolution of music

In our morning read-aloud, the author mentioned an 8-track cassette.  My kids had never heard of such a dinosaur.  I explained (which is one reason I still read aloud to my perfectly literate children): "An 8-track was what we used to listen to music on before cassette tapes were invented."  Blank looks.  "Cassette tapes were what we listened to music on before CD's were invented.  CD's were what we listened to music on  before mp3's were invented.  I remember listening to a Simon & Garfunkle 8-track repeatedly when I was a kid." They were glassed over by that point, and I realized just how incredibly old I really am.