Mother tongue education, however, goes far beyond just benefiting society. It is about preserving one's ethnic identity and culture. It is true that choosing one language for all can be a lot more efficient, but one must also be concerned with the loss of diversity. The fact that the world has so many languages is a precious heritage, but this treasure only remains if there are people who could still read, speak and write in these languages. Some advocates of mother tongue education even suggests that basic education in the mother tongue first would facilitate cognitive development faster in young children. Thus, there are proponents that now insist that all of basic education in the early years must be given in the mother tongue of a child. In a country like the Philippines, where there are so many languages, such is daunting task. In a previous post on this blog, Languages in the Philippines: A Challenge for Basic Education, it is pointed out that even in schools where one language is dominant, there are still a substantial number of students that speak a different language. Masbateño, for example, is a language spoken by a significant fraction of households in region 5 in the Philippines, and is the major language in the province of Masbate, but schools in Masbate have been designated to use Bicolano, a language distinct from Masbateño and spoken by the majority from Region 5. In addition, finding teachers that can teach all subjects in the native tongue of each pupil enrolled in any one of these schools is perhaps close to impossible.
To preserve the mother tongue of a child, continuing instruction beyond home and into preschool, kindergarten and the elementary years is needed. If this is the objective then having at least part of the instruction during these years in the native tongue can be very helpful. This is much less demanding than mother tongue based multilingual education. Most of the subjects can therefore be taught in a second language. Of course, there is concern that development in a second language may simply compromise development in the native tongue. At least, in this case, there is effort to preserve fluency in the mother tongue.
A study published in the journal Child Development addresses the question of what happens to a child's proficiency in a native tongue after going through school where the medium of instruction is a second language.