"RETENTION OF ENGLISH LANGUAGE KNOWLEDGE AMONG DIFFERENT AGE LEARNERS: AN EXPLORATORY MULTIPLE CASE STUDY IN DIFFERENT SOCIOLINGUISTIC CONTEXTS"

Abstract

"This study investigates how Vietnamese adult and young adult learners retain English vocabulary and grammar in semi-formal and informal settings (i.e., one-on-one tutoring lessons and self-directed learning through everyday exposure and use outside lessons). Using semi-structured interviews, lesson observations, and learner-produced artifacts, this study looks at the cognitive, affective, and social factors that influence retention. It also examines strategies learners use to consolidate and use English beyond instruction. Three participants were selected for this multiple case study: two adult learners (a husband and wife aged under 50) and one young adult learner (aged 21), representing different generational cohorts. Findings show that repeated retrieval, visual and multimodal support, scaffolded interaction, affective factors, autonomous learning strategies, and phonological encoding all play central roles in promoting durable retention. Across cases, participants who reported engaging in structured review, multimodal reinforcement, and self-directed practice also were associated with stronger retention and use of target forms than those relying mainly on initial exposure. The study highlights how cognitive processes, emotional states, and contextual affordances interact in sustaining vocabulary and grammar knowledge. The study offers implications for teaching practice, learner strategies, and institutional support, emphasizing retrieval-based instruction, scaffolded communicative tasks, multimodal reinforcement, focused pronunciation work, and the cultivation of learner autonomy. Limitations include the small sample size, reliance on self-report data, and the relatively short duration of observation, which may constrain the depth, transferability, and interpretive scope of the findings, Based on these limitations, recommendations are made for future longitudinal, experimental, and technology supported research to further examine retention processes across extended timeframes and diverse learning contexts. Overall, the study offers insights into sustainable language learning practices and the mechanisms of language retention among adult Vietnamese learners of English."