In this article, the author presents a set of design principles that were used to construct and refine a lesson involving the TI-Nspire handheld graphing calculator through multiple enactments in high school algebra classrooms to assist students in constructing a deeper understanding of systems of linear inequalities, a high school algebra content standard in the Common Core State Standards for Mathematics (CCSSM) (NGA Center and CCSSO 2010). These principles are rooted in years of crafting and implementing technology-based lessons in secondary school mathematics classrooms. Furthermore, they are research-based and aligned with the Common Core. These principles could be used to develop a technology-rich lesson as is done in this article or could be used as a framework to assist in revising a found resource. In this article, the author argues that using these principles to construct or adapt existing technological resources offers students opportunities to develop deeper mathematical understandings and nurture their capacity to investigate mathematics. This article also highlights the power of planning a lesson with others and reflecting on lesson implementation either alone or with others.