Moroccan Arabic-English code-switching among EFL teachers: Effect on students’ L2 vocabulary learning and retention

Teachers’ use of learners’ first language (L1), a phenomenon sometimes referred to as code-switching, has been a topic of great theoretical debate in the field of Second Language Acquisition (SLA) literature. Yet to date, there has been little research that has addressed the effect of teachers’ use of code-switching on second language learning itself. Therefore, the aim of this research paper is to examine the effect of teachers’ code-switching on students’ L2 vocabulary learning and retention. The study employed a quasi-experimental design to address the issue of teachers’ code-switching effect on vocabulary learning and retention. The study involved two intact classes of English as a Foreign Language (EFL) common-core students, each consisting of 30 participants, with one class receiving English-only instruction (Comparison group) and the other intact class receiving code-switching instruction (Experimental group). Under these two different instructional conditions, the participants were encouraged to learn a set of previously unknown English words, drawn from a reading text, through their teachers’ explanations. The results revealed that teachers’ code-switching to learners’ L1 (Moroccan Arabic) yielded better learning results, in terms of vocabulary gains, than English-only instruction, and this effect was maintained two weeks after instruction (retention). Having discovered these beneficial effects of teacher code-switching, the findings of the present research paper call for a reconsideration of pedagogical decisions regarding L2-only instruction, highlighting the importance of incorporating code-switching as a valuable tool in L2 vocabulary teaching, particularly for beginner-level learners.