While perusing YouTube for some longer length pieces, I came across "Symphony No. 40." It lasts about a half hour and would be another god addition to play in the background while kids are working. Or, you could set it up in a smaller station in the corner of a room.
What I like about this video is that it features a portrait of Mozart, which is a good teaching tool for the kids. What I do not like is the number of ads that you have to x-out in order to see his face. Most of them are links to other pieces, but nevertheless annoying. Still, it takes less than a minute to carefully remove all of them and then Mozart is visible.
What is your favorite Mozart to play in the classroom?