if a child comes from an arts impoverished environment, it might be a good idea to explain or show them things they hadn't seen or heard of before. or, take them to a museum , etc. especially if there are musical items as well. i think you have to keep it to music related art ideas - and only after the full lesson. ie giving them a book to read, a musical dictionary, asking them to go check out (library) art books and come back and tell you which painters they most identify with, cd's of music they haven't played before, recommending a concert, play, opera, or musical, this kind of stuff is probably good for every child.
some kids have an environment at home that fosters the arts - and they go to concerts, etc. maybe a trip as a class with the piano teacher to see a recital - or hear their teacher play - would inspire them, too.