This paper reports on a qualitative investigation into the use of Show and Tell tablet technology in mathematics classrooms. A Show and Tell application (app) allows the user to capture voice and writing or text in real time. Described here are the perceptions of 11 teachers during and after their exploration into the use of Show and Tell in their primary and secondary classrooms. These perceptions were used to evaluate Show and Tell tablet technology against a framework of student engagement and effective pedagogy. The results of the study indicated that the teachers perceived both the level and the quality of the students' engagement were high. Using Show and Tell apps enabled the teachers to enact effective pedagogy within their classroom practices. Importantly, through the use of Show and Tell recordings, students' thinking became visible to themselves, their teachers and other students in the class. This thinking then formed the basis of robust discussions and negotiation about the mathematical concepts and the strategies the students used to solve problems.