The educational landscape is becoming a digital learning environment. Students in today's digital world draw from multiple sources of information; from hypertext, videos, social media, to video games and internet searches (Luke, 2005). Emerging bilinguals, individuals learning two languages at once, who use software written in English have a passive relationship with the computer when software is not in their native language. They feel that this educational software belongs to another culture. This paper will present findings from a study with emergent bilinguals' engagement in a fully online pre-calculus course. The authors utilized the Cultural-Historical Activity Theory to describe how emergent bilinguals (perspective teachers) created authentic bilingual learning environments and improved their self-efficacy for mathematics. This study utilized Activity Theory to explicate the complex digital practices of emergent bilinguals while engaged in an online mathematics course. This mixed methods study was conducted over four semesters at a university on the U.S.-Mexico border. Data collected from demographic survey, class forum questions, daily logs with snapshots, self-efficacy surveys, and emails as well as face-to-face interviews, was analysed through a constant comparison method. Two tensions emerged from the findings, the importance of learning English and encountering unfamiliar Spanish dialects or translations. The results of this study demonstrated that emergent bilinguals mediated several forms of translators and culturally relevant videos for meaning making and to make cognitive connections with the topics in an online mathematics course. They further developed agency in creating an equitable educational digital space where they developed mathematical biliteracy.