One-on-one help from a teacher is highly impactful for students, yet extremely challenging to support in massive online courses (MOOCs). In this work, we present TeachNow: a novel system that lets volunteer teachers from anywhere in the world instantly provide 1:1 help sessions to students in MOOCs, without any scheduling or coordination overhead. TeachNow works by quickly finding an online student to help and putting them in a collaborative working session with the teacher. The spontaneous, on-demand nature of TeachNow gives teachers the flexibility to help whenever their schedule allows. We share our experiences deploying TeachNow as an experimental feature in a six week online CS1 course with 9,000 students and 600 volunteer teachers. Even as an optional activity, TeachNow was used by teachers to provide over 12,300 minutes of 1:1 help to 375 unique students. Through a carefully designed randomised control trial, we show that TeachNow sessions increased student course retention rate by almost 15%. Moreover, the flexibility of our system captured valuable volunteer time that would otherwise go to waste. Lastly, TeachNow was rated by teachers as one of the most enjoyable and impactful aspects of their involvement in the course. We believe TeachNow is an important step towards providing more human-centered support in massive online courses.

翻译：来自教师的一对一帮助对学生影响深远，但在大规模在线课程（MOOC）中极难实现。本文提出TeachNow：一种新型系统，使全球任意地点的志愿教师无需任何调度或协调即可即时向MOOC学生提供一对一辅导。TeachNow通过快速定位需要帮助的在线学生，并将其与教师置于协作会话中实现这一功能。这种自发、按需的特性赋予教师根据自身时间安排灵活提供帮助的能力。我们分享了将TeachNow作为实验性功能部署于一门为期六周、拥有9000名学生与600名志愿教师的在线CS1课程的经验。即使作为可选活动，教师仍通过TeachNow为375名独立学生提供了超过12300分钟的一对一辅导。通过精心设计的随机对照试验，我们证明TeachNow会话使课程学生保持率提升了近15%。此外，系统的灵活性捕捉了原本可能被浪费的宝贵的志愿者时间。最后，教师将TeachNow评为参与课程中最具愉悦感与影响力的环节之一。我们相信TeachNow是向大规模在线课程提供更人性化支持的重要一步。