Orta düzey yabancı dil olarak İngilizce öğrenen Türk öğrencilerin yazdıkları metinlerinde sözcük gelişimi: Bir açıklayıcı araştırma

The aim of this study is to analyze vocabulary development of Turkish EFL learners via the features of lexical density, lexical diversity, and lexical profile, their impact on the overall writing scores, the accuracy of certain academic words, and learners' and teachers' ideas on vocabulary development. An explanatory sequential mixed method research design was adopted, in which first quantitative data were collected through learners' essays and analyzed using Textalyser, Coh-Metrix, and Range, and qualitative data collection followed up via semi-structured interviews. The participants were eighty-seven first-year ELT students, and eight of these participants were selected thorough extreme sampling for qualitative data collection. The findings reveal that lexical density, lexical diversity, and lexical profile exhibit fluctuating patterns, and only lexical diversity and academic vocabulary have a statistically significant relationship with overall writing scores, as lexical diversity and Academic Word List (AWL) vocabulary predict 14.3% and 11% of the variance in writing scores respectively. The study also reveal that academic words selected showcase problematic recurring uses. Additionally, the interview results provide insights into vocabulary development and possible reasons of observed increase and decrease, revealing the impact of especially learning environment, resource integration, in-class experience and outside activities on fluctuating pattern on vocabulary development. Overall, the study highlights the significance of vocabulary development and use in the context of language education, discusses the potential factors contributing the fluctuations by offering valuable insights for educators and learners alike.