Erlkönig is a popular piece of voice repertoire that gets performed often in conservatories. So I remember hearing this at friends’ recitals when I was in school.
The piece is the setting of poetry of the same name by Goethe. It describes a Father and Son riding through the woods at night on horseback, being followed by Erlkönig (Elf King). The Father can’t see Erlkönig and eventually the son is killed. Schubert’s setting of this is clever in that he uses different ranges in the voice to represent the characters. So one single singer portrays all of parts.
My bassoon arrangement has the two middle bassoon parts do the heavy lifting by playing constant triplets. It makes for a good articulation exercise!
PDF of the score and parts is here Erlkonig Bassoons