Exploring students’ habits of using WhatsApp is important: such introspection helps students to reflect, and improve their actions. Habits are subconscious thoughts that drive students, for example, to use WhatsApp, even without concentrating on their learning actions. Habits are formed after students have repeated the same action. Twelve students, registered for a Bachelor of Education degree in Mathematics Education at a university in South Africa, were selected to participate. The objective of this study was to understand students’ habits of using WhatsApp in the learning of mathematics. Reflective activities, focus-group discussion, and one-on-one semi-structured interviews, framed by interpretive case study, were used for data production. The students’ habits revealed that The Tree Three Rings Theory was useful when applied as the learning framework. Such application of the theory generated three categories of habits of WhatsApp usage. Categories were social, discipline/disciplinary, and personal habits. The university at which these students were registered prescribed Moodle as the learning management system (LMS). However, the students mostly used WhatsApp. As a result, they used WhatsApp even during face-to-face classes. It appeared that students had been ‘captured’ by WhatsApp, using it as their ‘master’, instead of using it as both their ‘master’ and ‘servant’. The study concluded that, although there were elements of both personal and discipline habits, the social habits drove the learning. Consequently, this study recommends that students should reflect; using social, discipline, and personal actions as taxonomies of education habits, in order to address societal, individual, and the mathematics education needs.