Secondary school students are labelled as bad mannered, and low achievers because of their extent of using mobile devices. Elder siblings and parents have not supported these students use of mobile devices. In some cases, students have had their devices confiscated. Little do parents know; their children are using mobile devices for learning outside the classroom. Students view using their mobile devices for learning to be compatible with using textbooks and that as they use the devices outside the classroom, they are supplementing their learning. When confused, they contact teachers for clarification. To understand the extent of secondary school student’s use of mobile devices for learning outside the classroom in Tanzania, a single secondary school was purposively selected. A total of 202 students responded to questionnaire, and 20 students were interviewed by the researchers. The theory of diffusion of innovation was employed to provide an understanding of the phenomenon of interest. This research aims to debunk the myth on secondary school student’s use of mobile devices, equip students staying far from schools, and with less resources evidence of a tool they can use for learning, provide a theoretical elaboration on usage of mobile devices for learning, and apprise the informal learning community.