It all depends on the school, and on who's teaching there that year, doesn't it? My own school days started in around 1946 so are hardly relevant today, but we sang *lots* of folk songs, including having assemblies just to sing. Some of those early songs are still favorites.

My own kid is in high school now. I took my zither and MacArthur harp to his fourth and fifth grade classes, chose kid-friendly songs ("The Fox," "Camptown Races", "Mockingbird Hill"), and the kids loved it. A couple of times they asked me to sing a song twice! One year, the teacher said she was doing a unit on Folk Music at the time, so it fit right in.

Bruce Hutton, one of the founders of Double Decker String Band, is regularly brought into elementary schools in this area to give an assemblies. He brings a big selection of instruments, including some percussion stuff, and calls up a couple of kids from the audience to play along. Big hit. The music is old-timey folk, played on marvelous old instuments.