Adults in the lives of children (i.e., parents, mentors, teachers) play a wide range of roles that support youth learning and development. Teachers, for example, present content and organize projects, provide encouragement and access to resources, broker connections to people and learning opportunities, and prompt learners with feedback to revise and improve their work. Being able to interact with educators who can play these diverse roles in a way that builds relationships and helps them navigate into areas of interest and career pathways can be formative, particularly for underserved youth. In this poster, we ask, how can we better enable educators to provide individualized and equitable learning support to youth? Based on observations of mentors working with middle-school aged girls in a 10-week out-of-school STEM program, we describe how various learning support roles were played over the course of the program. We describe how stages of the program reflected different instructional activities and challenges. We then suggest visualization design principles for helping mentors address the challenges and opportunities of practice that were observed. This work contributes to a growing body of research aimed to promote equity in STEM learning in informal learning environments by exploring how data visualizations can be used to inform educator practice and the iterative design and development of STEM programs.