Digital learning resources are commonly employed to support learning in out-of-class contexts, either as a complement to the learning in formal classrooms or as an alternative that can be used by learners to pursue personal learning goals. This study identified a significant gap in the literature concerning children's use of digital technology to support STEM (science and mathematics in particular) learning outside of the classroom. To develop a framework for further research in this area, this study adopted a multiple case study design using semi-structured interviews and observations as data collection methods. Following a sociocultural framework, this research primarily confirmed existing work regarding the identification of motivational factors and concluded that the user interface (UI), all-in-one features of digital technology, simulation and alternative learning experience were factors that influenced the learning motivation of secondary school-age learners when learning science and mathematics with digital technology in out-of-class contexts.