Mobile technologies are quickly becoming tools found in the educational environment. The researchers in this study use a form of mobile learning to support students in learning about angle concepts. Design-based research is used in this study to develop an empirically-substantiated local instruction theory about students' develop of angle and angle measure. This local instruction theory involves real-world connections and mobile technologies through a sub category of mobile learning called context-aware ubiquitous learning. Through a process of anticipation, enactment, evaluation, and revision, the local instruction theory was developed to include a theoretical contribution of how students come to understand angle and angle measure using context-aware ubiquitous. A set of instructional activities was also developed as an embodiment of that theory. The findings from clinical interviews indicate that context-aware ubiquitous learning is a valuable mathematical context for introducing students to angle and angle measure.