The third (scherzo) movement of a concerto for Cello and orchestra I wrote a few months ago based on some Appalachian folk songs. Here the Cello has a back and forth with other instruments (or groups of instruments) in the orchestra.
Here's a list of what's happening in this part:
0:00 The first song "Charlie Sweet", played by the Cello contrasted by other instruments in the orchestra
1:31 The second song "Darlin Corey" forms the middle section (trio)
2:43 The first song returns followed by a brief Coda to finish the piece.