GENOA, Neb. — In a remote patch of a long-closed Native American boarding school, near a canal and some railroad tracks, Nebraska’s state archeologist and two teammates filled buckets with dirt and sifted through it as if they were searching for gold. They’re trying to find the bodies of dozens of children who died at the school and have been lost for decades, a mystery that archeologists aim to unravel as they dig in a central Nebraska field that was part of the sprawling campus a century ago. People toting shovels, trowels and even smaller tools are searching the unmarked site where ground-penetrating radar suggested a possible location for the cemetery of the Genoa Indian Industrial School. Genoa was part of a national system of more than 400 Native American boarding schools that attempted to assimilate Indigenous people into white culture by separating children from their families and cutting them off from their heritage.