Temporal Dynamics of EFL Learners’ Oral Proficiency: Effects of Coursework and Self-Training Using Shadowing-Based Tasks

In EFL (English as a Foreign Language) environments, opportunities for learners to use the language outside the classroom are often limited, making it challenging to foster oral proficiency. This study examined the effects of spring semester coursework and summer self-training on the oral proficiency of 217 Japanese university students. It addressed 2 research questions: (1) changes in oral proficiency across the spring semester and subsequent summer vacation, and (2) the effects of intensive self-training during the vacation period. Semester instruction followed a flipped learning model, and summer training consisted of shadowing and related oral tasks. Oral proficiency was assessed using the Versant Speaking Test sub-scores. Results showed that mean scores improved during the spring semester but either plateaued or declined during the summer break. However, learners who actively engaged in summer self-training demonstrated small gains in fluency and pronunciation, suggesting the potential of autonomous practice to help sustain procedural oral skills. 英語が外国語として学ばれる環境（EFL）では、教室外での使用機会が限られるため、学習者の口頭能力の発達を促すことが難しい。本研究では、日本の大学生217名を対象に、(1) 春学期と夏季休暇を通じた口頭能力の変化、(2) 休暇中の集中的な自己トレーニングの効果を検討した。学期中はflipped learning型の授業を行い、夏休みにはシャドーイングおよび関連課題による自己練習を行った。Versant Speaking Testの4つのサブスコアを4月、7月、9月に測定した結果、春学期には全体的な向上が見られたが、休暇中は停滞または低下が生じた。一方、夏休み中の自己練習に積極的に取り組んだ学習者は、流暢さと発音において小さな向上を示した。これらの結果は、教室活動と自己練習の両立が口頭能力維持に有効であることを示唆している。