The PIRPOSAL model is both a conceptual and pedagogical framework intended for use as a pragmatic guide to classroom implementation of Integrative STEM Education. Designerly questioning prompted by a "need to know" serves as the basis for transitioning student designers within and among multiple phases while they progress toward an engineering solution that will function as prescribed in the specifications of the social/ human need. These transitions are both dynamic and fluid, engaging the learner for various intervals of time, from fleetingly considering a concept or idea to more lengthy periods of thoughtful attention, depending on the questions posed. In this way, driven by the centrality of questioning, the eight phases of the PIRPOSAL model reflect authentic designerly practices occurring in their natural, non-linear fashion based on the designer's need to know. This article is the first of two articles explaining the conceptual framework regarding how components of the PIRPOSAL model convey theory to practice.