Aim/Purpose: In this paper, we analyze the phenomenon of "classroom WhatsApp groups", in which a teacher and students from a particular classroom interact with one another, while specifically focusing on the student perspective of these interactions. Background: The instant messaging application WhatsApp enables quick, interactive multimedia communication in closed groups, as well as one-on-one interactions between selected group members. Yet, very little is known about the extent, nature, and purposes of these practices, the limitations and affordances, the type of discourse and conflicts that develop in these spaces, and the extent to which it affects teacher-student interactions outside of WhatsApp (e.g., the social climate in class, the teacher's status, teacher-student and student-student relations), especially from the students' perspective. Methodology: Our methodology combines questionnaires, personal interviews, and focus groups with Israeli secondary school students (N = 88). Contribution: The present study adds to the expanding body of empirical research on social media use in educational settings by specifically focusing on a heretofore underexposed aspect, namely, secondary school student-teacher communication in the popular instant messaging application WhatsApp. We report on findings from the student perspective and discuss the advantages and limitations of this form of communication sphere, and on the social functions of the different classroom WhatsApp groups in secondary school students' everyday life. Findings: The combined findings reveal that classroom WhatsApp groups have become a central channel of communication for school-related topics. It is used primarily for organizational purposes (sending and receiving updates and managing learning activities), as well as a means for teachers to enforce discipline. Students mentioned many advantages of WhatsApp communication, such as easy access, the ability to create communities, the ability to safeguard personal privacy, and the communication format (written, mediated, personal, or group). However, they also recognized limitations (i.e., communication overload) and challenged teacher ability to monitor and affect student interactions in social media, even when they are present in these WhatsApp classroom groups. Finally, we report on the role of parallel, sans-teacher WhatsApp groups, which are characterized as back stage discourse arenas that accompany the front stage offline classroom activities and the "official" classroom WhatsApp group. Recommendations for Practitioners: The combined findings of this study indicate how WhatsApp-based, joint teacher-student groups can serve a variety of educational purposes, namely, organizational, instructional, and educational-disciplinary. In addition, and in spite of teachers concerns, students are aware of the challenges inherent to the use of WhatsApp for communication with their teachers. Some of the main characteristics that prevent teachers from using other ubiquitous digital communication media, such as Facebook or Twitter, are not relevant when it comes to WhatsApp. Both teachers and students view WhatsApp as a favored channel of communication because of the low exposure to personal information and minimal invasion of privacy. Future Research: The qualitative methodology of this paper limits the ability to generalize the current findings to other contexts and population groups. Future research should preferably explore the generalizability of our findings to larger sections of teenage populations. It should also explore similarities and differences with other age groups. Finally, the present study was set in a particular country (Israel). Local norms of cellphone use and of appropriate teacher-student interaction, as well as locally developed media domestication patterns, may differ from country to country and/or from one cultural group to another. Future research should then include and compare the current findings with data from different countries and cultures in order to complete the picture. [ABSTRACT FROM AUTHOR]