The Death of the Centaur(1991)

Dan Simmons

A summer-school teacher uses tales of fantasy to evoke interest in his students. The tales take place on Hyperion, concerning a centaur from the Sea of Grass named Raul (which is, interestingly enough, Endymion's first name) and his battles with The Shrike. Although set in the Hyperion universe, this story is not found in any of the novels.