One place I'd start is the music of Leadbelly (Huddie Ledbetter). He does lots of kids songs. If you need details let me know. He does lots of African-American folk songs. There are some history lesson type songs:

"Cotton Song," WORK-

"We Shall Be Free," EMANCIPATION-

"Bourgeois Blues" STATUS-

"Hitler Song" WWII


Let me know if you need any more help,

-Richie