Advocacy of STEM curricular approaches is based on a concern to engage students in authentic disciplinary and interdisciplinary practices in the STEM (science, technology, engineering, mathematics) disciplines, and the need to promote participation in STEM pathways. The "STEM Academy" professional learning program was developed to support teachers to engage and motivate students by creating real-world, challenging problems. The initiative involved interdisciplinary teams of secondary STEM teachers attending workshops and working with university experts to design, implement and evaluate STEM curricular experiences. This paper focuses on case studies undertaken in two of the twelve schools involved in the initiative, using interview data from teachers and students, to explore the nature of their programs and their experiences. We investigate key features of these two schools' approaches, using a conceptual framework for integrated STEM, and explore the challenges and benefits of different features of integrated STEM that promote different dimensions of engagement in learning mathematics. We explore how the framework characteristics can be reframed into four dimensions that promote mathematics engagement in integrated STEM education--design thinking in authentic contexts, content integration, STEM practices and 21st Century skills, and exposure to professional practice.