I’ve recently stumbled upon a rich resource of music from dozens of great classical composers (among other styles of music). All the recordings on this site are free and in the public domain. There are no copyright restrictions either, which means these recordings can be freely used for any purpose anywhere for any reason.
The site is called musopen.org and I have found it helpful as I search for quality royalty-free music that I can use in my juggling show. This music can be used for anything, like your classroom, your movie you’d like to make, or a remix you’d like to create. I especially like some of the songs by Berlioz, Sousa, Bach, Mozart, and Beethoven.