The bicultural Ha:san Preparatory and Leadership School, a charter high school with predominantly Tohono O'odham students, is located close to the University of Arizona (UA) in Tucson AZ, permitting mutually beneficial collaborations. The school, in communication with NSF’s NOIRLab, identified math tutoring as an area for growth. Beginning in 2018, Mentorship and Education in SCIence for Tucson (MESCIT) formed at Steward Observatory to match University of Arizona students with high school tutees. This enabled personalized one-on-one and one-on-two math tutoring sessions to fill knowledge gaps and practice skills in Algebra and Geometry. These tutoring sessions provided the undergraduate students with greater cultural understanding and teaching experience while also helping high school students work on critical math skills. Tutees who attend these sessions are given an in-person (or 2020 virtual) experience at the University of Arizona, where they gain mentorship and exposure to pathways through higher education from Native American undergraduates in Science Technology Engineering Math (STEM) majors, watch a planetarium show and eat lunch on campus. Analysis of tutor feedback shows that regular interactions with students over more than 12 sessions are needed to fully build trust and make improvements to students’ understanding and confidence. The Ha:san Preparatory and Leadership School and the University of Arizona now have a close relationship benefitting both institutions. Partnership is crucial for astronomy, as many observatories rely on Native American lands including Kitt Peak on the Tohono O’odham reservation.