The Effect of Reading and Vocabulary Intervention within the Test Validity on Depth and Breadth of Vocabulary Knowledge among Iranian EFL Learners

Because intervention within the test validity as a dynamic assessment (DA)-laden procedure has been newly proposed by scholars in the field, research scarcity is there with respect to this procedure within EFL studies. This study examines the effect of vocabulary and reading intervention within the test validity on depth and breadth of vocabulary knowledge among EFL learners through a quasi-experimental pre-test post-test control group design. Three intact groups of intermediate female EFL learners, each composed of 30 learners, participated in this investigation from a private language institution in Tehran through convenience sampling. Data were gathered through the administration of the Quick Placement Test (QPT), the Vocabulary Levels Test (VLT), and the Depth of Vocabulary Knowledge Test (DVKT). To analyze the data, ANOVA was used. It was shown that reading and vocabulary intervention within the test validity had a significant impact on Iranian EFL learners’ depth and breadth of vocabulary knowledge. Moreover, there was a significant difference between the effectiveness of reading and vocabulary intervention within the test validity on depth and breadth of vocabulary knowledge in favor of the vocabulary intervention within the test validity. The findings carry implications for EFL instructors, learners, and curriculum developers.