People in many African communities live within a series of concentric circles when it comes to language. In a small group, a speaker uses an often unwritten and endangered mother tongue that is rarely used in school. A national indigenous language—written, widespread, sometimes used in school—surrounds it. An international language like French or English, a vestige of colonialism, carries prestige, is used in higher education, and promises mobility—and yet it will not be well known by its ...