本研究探討數位環境下大學生課堂中的注意力流動與學習投入現象，並重新思考當代高等教育中「在場」的意義。研究採探索性案例研究取向，以研究者所授大學課程為研究場域，透過課堂調查和學生回饋資料，了解學生於不同課堂型態中的手機使用經驗與注意力切換情形。研究結果顯示，在本研究案例中，部分學生雖實際出席課堂，其注意力仍可能在課堂活動與數位媒介之間移動，呈現形式出席與實質投入未必一致的現象。學生提及的手機使用原因除課程相關資訊查詢外，亦包括通知干擾、社群互動、習慣性滑動、情緒調節及疲勞紓解等因素。研究進一步提出，在數位環境下，學生的「在場」可從身體、注意力、心理及意義等不同層面加以理解。最後，本文討論數位環境對課堂參與的可能影響，並提出課程設計與教學實務上的若干思考，作為未來研究與高等教育教學實踐之參考。

This study explores the phenomenon of attention flow and learning engagement among university students in digitally mediated classrooms and reconsiders the meaning of “presence” in contemporary higher education. Adopting an exploratory case study approach, the research was conducted in a university course taught by the researcher. Data were collected through classroom surveys and students’ feedback to examine students’ experiences of smartphone use and attention switching across different classroom formats. The findings suggest that, within this case, some students were physically present in class while their attention frequently shifted between classroom activities and digital media, indicating that physical attendance and genuine engagement do not necessarily coincide. Students reported using smartphones not only for course-related information seeking but also in response to notifications, social interactions, habitual scrolling, emotional regulation, and fatigue relief. Based on these observations, the study proposes that students’ “presence” in digital learning environments can be understood through multiple dimensions, including physical presence, attentional presence, psychological presence, and meaningful presence. Finally, the study discusses the potential implications of digital environments for classroom participation and offers reflections on course design and teaching practices as references for future research and higher education pedagogy.