This paper reports on findings from a five-teacher, exploratory case study, critically observing their implementation of a technology-intensive, augmented reality (AR) mathematics curriculum unit, along with its paper-based control. The unit itself was intended to promote multiple proportional reasoning strategies to urban, public middle school students. The participants were select via purposeful sampling with 2 scoring highly, 2 low, and 1 medium on a measure of mathematical knowledge for teaching (MKT). The researcher used lesson transcripts, observation field notes, and teacher electronic journals, along with pre-/post-interviews and pre-observations/surveys to explore the influence of teacher mathematical knowledge on their implementation of the unit and to examine differences in implementation between the AR and board game control versions of the unit. More specifically, the researcher focused on whether teacher MKT or technology-based materials influenced the types of adaptations teachers made to mathematical task structure, general quality, and mathematical quality. In terms of technology, there was less mathematical substance and there were more adaptations to task structure and mathematical task quality during the AR implementations, which no discernible patter for general task quality. For MKT, the paper highlights the case of low-scoring teacher Ellen whose implementation demonstrated lower mathematical quality than the higher-scoring teachers which aligns with what the mathematics education research would predict. However, she devolved task cognitive demand less often and used student thinking more often than the higher-scoring teachers, which is inconsistent with existing research. In the final piece, current benefits and limitations of using AR to teacher mathematics, along with next steps for the work are presented. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]