A unique project in Israel, “Bagroup,” used the WhatsApp social media platform to aid students preparing for their mathematics matriculation (Bagrut). Three months prior to the exam, high school students studying five-level mathematics were invited to join this project in which teachers offered blended learning and students could review the material and get help when required. Bagroup’s uniqueness lay in its setup: each group comprised 100 students and a teacher who were not familiar with one another, in contrast to “normal” classroom-based WhatsApp groups where the participants and teacher know each other. A comprehensive mixed method study in 2018 examined teachers’ and students’ perspectives on the Bagroup project using questionnaires, interviews, and observations. This chapter focuses on the teachers’ perspectives. Overall, the teachers believed that Bagroup offered many advantages, specifically its 24/7 availability, accessibility, focus on peer learning, anonymity, and the social-emotional support it offered. Disadvantages were mainly the difficulty involved in not “seeing” the students, an inherent lack of motivation for some students (both of these facets of the anonymity), and—especially for mathematics—the difficulty of presenting mathematical notation on the WhatsApp platform.