Some call it the toughest, roughest dogsled race in the world. We call it a GIGANTIC history lesson This comprehensive guide enhances the many dramatic learning opportunities students can gain from reading The Mystery on Alaska's Iditarod Trail by Carole Marsh. Some call it the toughest, roughest dogsled race in the world. We call it a GIGANTIC history lesson This comprehensive guide enhances the many dramatic learning opportunities students can gain from reading The Mystery on Alaska's Iditarod Trail by Carole Marsh.