Approaches to integrated STEM education offers opportunities as well as challenges for both teachers and students. Working on problems or projects involving more than one of the STEM disciplines gives access to interesting, motivating and relevant real-world contexts and problem situations, but at the same time increases the complexity of the problems and problem solving process. One contributing factor to this increasing complexity is the need to appreciate, negotiate and coordinate the different perspectives on the nature of knowledge and the characteristics of inquiry in the different STEM disciplines. This paper outlines and discusses a proposal for how so-called Fermi Problems and Fermi Problem Activity Templates (FPATs) can be used as a tool for teachers and students to start navigating and tackling this complexity.