Abstract:

Bilingual education is becoming more common throughout the world. There is no doubt that bilingualism comes with important advantages. The benefit of bilingualism has been shown even to extend to basic cognitive functions, namely to an improved ability of executive control.
However, educational practitioners need to be aware that bilingual learning also comes with costs. They can not expect that the information learned in one language can be retrieved in another language as well as in the language of instruction. But only little research has been done on the underlying cognitive mechanisms of learning in bi- or multilingual pedagogical settings. Despite of the obvious benefits and popularity of immersion education it is far from clear whether or not there are any risks for students who are trained in such programs.

The aim of our research is to investigate the possible costs and the negative effects of bilingual education. In particular, it is necessary to identify and investigate the extent of the cognitive costs in situations when languages of instruction and of application are different.

The formulated problem is fundamental, both in national and international contexts. The above situation arises, for example in secondary schools of Russia with native (Yakut, Tatar, North Ossetian, Circassian etc.) language of instruction, in which mathematics is taught bilingually by means of Russian and native languages. The teachers are using bilingual mode of teaching mathematics due to the fact that the Unified State Exam in mathematics is compulsory for all students of the Russian Federation, and it is conducted in Russian language.
The interpretive approach was used in which data was collected by the transcription of video recordings of lessons and analysis of interviews with students and teachers. The data was analyzed both qualitatively and quantitatively.

Cognitive costs were investigated in the process of solving mathematical problems using two languages (Russian and Tatar) by students and pupils of schools and Universities in Tatarstan. Classification of language switching was suggested on the basis of observations of real bilingual study of mathematics in high school. All code switching were divided into 4 categories: "reformulation", "translation", "terminology", and “support". The hypothesis that the negative effects from language-switching occur in the form of a time delay and deterioration of the accuracy of the solution of math problems was confirmed.

Keywords:

Cognitive, cost, bilingual.