native-language instruction is the practice of teaching schoolchildren in their native language instead of in the official language of their country of residence.
Foreigners on a temporary visit abroad often prefer this, believing that it will keep their children from falling behind their peers at home as they struggle to master a foreign tongue and culture. Japanese on business trips to the United States sometimes send their children to private schools where they are taught in Japanese. The US government maintains schools for its diplomatic and military personnel stationed in such areas as Europe and the Far East.
Native-language instruction has also been advocated for the children of recent or longtime immigrants in many Western countries, particularly the United States. In this context, it is often called "bilingual education". Advocates tout this over what was previously the sole alternative, i.e., full immersion.
Many aspects of native-language instruction are controversial:
- What sorts of ESL programs should accompany it? (Why should ESL accompany?)
- Should it be called "bilingual education"? (Bilingual Education is when there are two languages used for educating, if that is the case then, yes it should be called Bilingual Education.)
Advocates differ on which approach better promotes academic achievement for immigrant children. Both sides cite studies "clearly proving" that:
- teaching students in their native language "is shown to close the gap better and faster than English Immersion" 
- ESL students perform far better than bilingual students on reading and math exams 
Some touted native-language instruction as a way to help immigrant children resist assimilation into American culture.