ALBUQUERQUE, N.M. (AP) — Albuquerque city officials plan to use ground-penetrating radar as they research the history of a site where dozens of Native American boarding school students are believed to have been buried more than a century ago. They also plan to use orange markings at the city park to signify the importance of the site. Orange is the color used to symbolize the movement that is bringing more awareness to the troubled legacy of the boarding school system. Indigenous activists became concerned earlier this year when a plaque memorializing the students from the former Albuquerque Indian School disappeared. They established a makeshift memorial and called for an investigation.