What does it mean to pick a musical work from a music genre and describe a characteristic? Where do children's songs fit into a genre?

In order to pick a musical work from a specific genre, one must choose a genre, which encompasses any different type of music. Victorian or Baroque music styles are different genres, while rock and roll is its own genre. Select a genre of music, and then identify a piece of music that fits that style.
To describe a characteristic, simply find something common about that genre. For instance, if you are discussing Baroque music, you could select aspects such as the typical instruments that were included—like flute, harpsichord, or orchestral strings. Or perhaps you'd discuss the thematic similarities in rock and roll music of the 1980s that has a rebellious nature and frequent use of slang in the lyrics.
Children's songs could be considered a genre all on their own, because they have a simplistic style and are intended to be both educational and entertaining. However, children's music can also be said to fit in the various genres of the eras in which the pieces were written—for instance "Au Clair de la Lune" is more of a classical piece, while the music of various Disney movies falls into various show tunes, rock and roll, or even jazz genres.