A scalp from the Sand Creek Massacre of 1864, where dozens of American Indians were murdered by Union soldiers, sat in the depths of the Denver Museum of Nature and Science for decades. The Cheyenne and Arapaho asked for it back, and the museum returned it, but it took years. For the current curator of the museum, the episode raised the question: Who owns the past? His new book explores the fight to reclaim American Indian culture. Later in the show, why Boulder and Denver have the biggest "achievement gaps" among Colorado's largest school districts.