Classroom Vocabulary Learning: Investigating the Role of Task Types on Iranian High Schools Learners of English as a Foreign Language

Abstract The present study investigated the efficacy of task types on the vocabulary learning of Iranian learners of English as a foreign language (EFL) whose opportunities for communication outside classroom context are limited. Moreover, the effectiveness of using Task-based Instruction (TBI) was investigated in this study. Data were collected from three classes of lower-intermediate high school students who were selected on the basis of availability and were taught for eight weeks. Each class was taught through one of three different task types: information-gap, opinion-gap, and reasoning-gap. The results of an achievement vocabulary test administered to the students of the three groups at the end of the instruction and a qualitative think-aloud report protocol analysis showed that the reasoning group outperformed the other two groups. Implications of the study are proposed for teaching and learning English as a foreign language in Iran.