Finding the sweet spot: Learners’ productive knowledge of mid-frequency lexical items

Research into vocabulary knowledge often differentiates between breadth (how many words a person knows) and depth well the are known). Both theoretical categories essential for understanding language learners’ lexical development, but how different aspects of interconnect has not received same attention as each individual dimension, especially in terms productive knowledge. This study analyses lexis from mid-frequency lemmas K3–K9 frequency bands learner corpus PELIC (The University Pittsburgh English Language Institute Corpus). Critically learners, mastery this range is achieving proficiency required university study. From these items, dataset 7,554 tokens were collected word families with multiple derivations manually annotated. The findings showed high rates collocational derivational accuracy forms learners opted to use. However, compared expert speaker texts Corpus Contemporary American (COCA), overused verb underused noun items. These patterns provide evidence interplay usage, suggesting that increased will naturally lead greater vice versa. Pedagogical implications reaffirm importance developing explicit morphological awareness accuracy. Suggestions items prioritize learning also provided, view helping achieve academic readiness.