In this paper, we share a mentorship model we developed and implemented while collaborating with pre-service teachers (PSTs) on their Model Eliciting Activity projects and the outcomes of the mentorship model in terms of PSTs' growth as teachers as well as researchers. For their projects, PSTs designed and developed their own mathematical modeling tasks and later analyzed student work collected during task implementations to better understand their students' reasoning. The PSTs' reflections were collected to assess the effectiveness of the program and to report their professional growth. The PSTs who participated in this mentorship model identified core teaching practices (e.g., questioning, facilitating discussions) and they improved their knowledge of student thinking and reasoning. They were also able to analyze rich data and identify trends in student learning. The findings from this study affirm that engaging in undergraduate research provides PSTs with opportunities to improve their teaching practice as well as their understanding of research processes.