全英語授課最近已成全球趨勢；世界各大學為提升競爭力並爭取國際學生就讀，已紛紛開設全英語授課之學位或課程。因應全英語授課的快速成長，有不少文獻已開始藉由研究政府及學校政策、探討教師及學生之觀點，以了解全英語授課的影響。然而，卻較少研究實際探討全英語授課對於學生學術表現的成效。此外，雖然已有研究發現全英語授課教師雖不會以教語言為主要課程目標，仍會在某些時候教導學生語言知識以幫助他們了解領域內容（e.g., Costa, 2012）；但此類研究卻極為缺乏。若想要從各角度探討全英語授課對學生的學習成效，深入瞭解全英語授課教師的教學過程是必要的。因此，本研究將試圖填補以上研究缺口，並提出兩個主要目標：第一，利用語言相關片段之研究概念，本研究將觀察全英語授課教師之語言相關片段的頻率及類型。第二，本研究將檢視全英語授課及語言相關片段對於學生學術及領域單字學習的成效。綜觀目前文獻，本研究為少數同時仔細探討全英語授課之過程及客觀成效的研究之一。在高等教育全英語授課已成不可避免且越來越普遍的情形下，本研究結果將能提供全英語授課研究寶貴的深刻見解，並提出實際教學建議以將全英語授課之正面效益極大化。English as a medium instruction (EMI) has become a growing global trend; universities around the world have established EMI programs or courses to gain competitive edge and to attract international students. In response to this fast growth, increasing literature has studied the influences of EMI by investigating government/university policies, and the perspectives of instructors and students. However, relatively little research has examined the effects of EMI on students’ performance. In addition, although it has been found that EMI instructors, while not teaching language, would sometimes attend to language aspects to facilitate students’ learning (e.g., Costa, 2012), research on EMI instructor’s attention to language is scarce. An understanding of EMI instructors’ practices is needed to evaluate the effectiveness of EMI from different angles. This study thus attempts to address the above gaps with two aims: first, using the construct of language-related episodes, this study will identify the frequency and types of instructor-initiated language-related episodes in EMI courses; then, this study will examine the effects of EMI and the episodes on students’ academic and disciplinary vocabulary development. This study is one of the few attempts that closely look at both the process and the objective outcome of EMI instruction. The findings will provide valuable insights in EMI research and practical implications on maximizing the benefits of EMI in higher education, where EMI will become indispensable.
English medium instruction