It's really difficult to suggest songs without a clearer idea of the intended use and users. If you are looking for background music, you can't go wrong with classical music. Instrumental music is less likely to intrude on the learning activity than will vocals. Age appropriate may be fine for listening but not for participating since, with most of your students, chronological age may not match developmental age. Also, I would definately avoid "pop" music because it would be a distractor. Most children's performers have slow songs--Raffi's Douglas Mountian--Tom Chapin's "I don't like to Say Goodbye", This Pretty Planet,etc.
I've used music with special needs children, (under 14) and had good results with songs they can move to, songs about animals, kid friendly music. By the way, small bean bag stuffed animals make great, safe rhythm instruments.