There is a sense of disbelief in this Sierra Leonean village as people weep in front of the bodies of two teenage boys wrapped in white cloth. The day before, 16-year-old Mohamed Bangura and 17-year-old Yayah Jenneh left their homes in Nyimbadu, in the country’s Eastern Province, hoping to earn a little extra money for their families. They had gone in search of gold but never returned. The makeshift pit they were digging in collapsed on them. This was the third fatal mine accident, leaving a total of at least five children dead, in the last four years in this region. Mohamed and Yayah were part of a phenomenon that has seen a growing number of children missing school in...