Everything you need to understand or teach Star Gate by Andre Norton.
StarGate, the story of a world called Gorth, contains a strong folk epic flavor in the tradition of Beowulf (10th century). The struggle between good and evil is a continuing theme represented in the adventures of her hero, Kincar. He must leave his world to avoid seeing his followers slaughtered by those who are determined to rule Gorth. By chance he comes upon a fight between bandits and a group of men called Star Lords. He is accepted by them and joins their adventure, passing through a "gate" into a "parallel world." As Kincar leaves Gorth he is given a mysterious stone by the dying old chief, Wurd. The stone glows at certain moments and can become quite hot. While he does not understand its mysterious powers, it seems to serve as a protecting force for Kincar. Those who dare to touch the stone...