Dr. Selfridge Music (tons of music and videos, etc.)
Free Sheet Music (a buuuuunch of songs)
Musical Snippet : Use Flat For Docs Chrome Extension to write your own music in Google Docs or Google Sides. Don't know how to use Musical Snippet? Click here for a quick tutorial. Don't know how to add a Chrome Extension? Follow these steps:
Go to the Chrome Webstore .
In the search box, type "Flat for Docs."
Click Add to Chrome.
Soundation (login with Google)
Patatap.com (use the keys on your keyboard to create sounds)
Kelly Riley Online (for younger kids, but still kinda fun)