A Validation Study

The use of L1 in language classroom has been traditionally repressed by applied linguists. However, in recent years, it is believed that switching to L1 can be considered a pedagogical instrument by teachers rather than a heterodox. Consequently, this two-phase study was an attempt to investigate the functions that are fulfilled by EFL teachers through their use of L1. In the first phase (i.e., theoretical phase), a thorough analysis of the available literature on teacher codeswitching was conducted with the aim of developing a typology which would encompass various functions of teachers ’ L1 use. In the second phase (i.e., empirical phase), in order to test the construct validity of the typology, data was collected from four EFL teachers by videorecording an entire session of their teaching. The instances of codeswitching in their performance were transcribed and coded in the light of the typology. The results of data analysis indicated that the typology has external manifestations in teachers ’ instances of codeswitching. It was also discovered that, among the selected participants, L1 was mostly used to fulfill pedagogical functions rather than social ones. Implications of the findings are discussed and suggestions for further research are provided