Several recent curriculum reforms aim to address the shortfalls traditionally associated with mathematics education through increased emphasis on higher-order-thinking and collaborative skills. Some stakeholders, such as the US National Council of Teachers of Mathematics and the UK Joint Mathematical Council, advocate harnessing the affordances of digital technology in conjunction with social constructivist pedagogies, contextual scenarios, and/or approaches aligned with Realistic Mathematics Education (RME). However, it can be difficult to create technology-mediated, collaborative and contextual activities within a conventional classroom setting. This paper explores how a combination of a transformative, mobile technology-mediated approach, RME, and a particular model of 21st century learning facilitates the development of mathematics learning activities with the potential to increase student engagement and confidence. An explanatory case study with multiple embedded units and a pre-experimental design was conducted with a total of 54 students in 3 schools over 25 hours of class time. Results from student interviews, along with pre-test/post-test analysis of questionnaires, suggest that the approach has the potential to increase student engagement with, and confidence in, mathematics. This paper expands on these results, proposing connections between aspects of the activity design and their impact on student attitudes and behaviours.