Document Type : Research Paper


1 PhD in Applied Linguistics (TEFL); 1) Department of General Courses, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; 2) Department of English Language Teaching, Ahvaz Branch, Islamic. Azad University, Ahvaz, Iran

2 PhD Student in TEFL, Department of Foreign Languages and Linguistics, Shiraz University, Shiraz, Iran

3 Assistant Professor, Department of English, Faculty of Humanities, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran


This investigation aimed to inform instructional practices that foster linguistic development and enhance the overall language learning experience by unraveling the nuanced dynamics at play. To this end, the researchers explored the influence of two distinct vocabulary books, "Keyword for Fluency" and "1100 Words You Need to Know," on language growth, willingness to communicate (WTC), and academic engagement within the upper-intermediate learner demographic. With 40 participants in the experimental group (EG) exposed to "Keyword for Fluency" and 40 participants in the control group (CG) using "1100 Words You Need to Know", all demonstrating upper-intermediate language proficiency, a concurrent mixed-methods research design was employed. A comprehensive teacher-made test was designed and administered to gauge language growth. The EG received targeted instruction based on "Keyword for Fluency," while the CG adhered to conventional language teaching methods centered on "1100." Our findings showcased substantial language growth, increased WTC, and enhanced academic engagement among participants in the EG as opposed to the CG. This study offers valuable insights for educators, curriculum designers, and researchers seeking to optimize vocabulary instruction strategies for upper-intermediate learners.


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