There is this pretty cool platform that I happened upon when I was putting together my initial, 1st week of school playlist... Boil The Frog.
Yup, you read it correctly. Boil. The. Frog.
When you first go to the site, you're asked to put in two musical artists. There is then a playlist created. The platform will then "take the listener from one style of music to the other" without you even noticing... sort of like you would cook could stew. You take your time and make it slowly until it is bursting with flavor.
So if you're stuck on building your class playlist, this is a cool and quick way to start.
BUT, this does not guarantee that all of the songs will be "school and age-appropriate"!!! Still, a cool place to start though. :)
"Our Class Playlist" Google Forms Doc can be found at www.TheGOATEducator.com under "Teacher Resources".