The language policy adopted by an educational system is without doubt one of the most powerful forces in language management. After religious institutions like churches, mosques, and synagogues, the school is the most likely to confirm or conflict with the pattern of home language use. In fact, most children find a serious gap between the language of their home (commonly a colloquial variety or dialect of the local language) and the language of school, most commonly aimed or claimed to be the national or official language. Many also find a gap between the home where they are encouraged to speak and the classroom where they are trained to keep quiet until called on.

This language gap is true not only of undeveloped third-world multilingual countries like Africa (Alexandre 1968; Brock-Utne and Hopson 2005), or of aboriginal minority groups like the Innu in Labrador (Burnaby and Philpott 2007), but of developed nations too. In Belgium, 40 percent of high school children reported such a gap, a result of the difference between the official Dutch and French taught in school and the dialectal varieties they speak at home (Aunger 1993). And of course with the rising level of migration worldwide, this home–school language gap is likely to increase rather than decrease.

The effect is enormous: first, when teacher and child do not understand each other's speech, teaching and learning are severely impeded.