In the USA, proponents of the practice argue that it will help to keep non-English-speaking children from falling behind their peers in the interim between immigrating and mastering English. Opponents of bilingual education argue that it delays students' mastery of English, thereby retarding the learning of other subjects as well. In California there has been considerable politicking for and against bilingual education. Much of the argument against hinges on the idea that California is in the United States and that everyone in the US should learn to speak English.
In Japan, the need for bilingualism (mostly Japanese and English) has been pointed out, and there are some scholars who advocate teaching children subjects such as mathematics using English rather than Japanese. As part of this proposal, subjects such as history, however, would be taught solely in Japanese.