  Physics outreach programs provide a critical context for informal experiences
that promote the transition from new student to contributing physicist. Prior
studies have suggested a positive link between participation in informal
physics outreach programs and the development of a student's physics identity.
In this study, we adopt a student-focused investigation to explore the effects
of informal programs on dimensions of physics identity, sense of community,
21st century skill development, and motivation. We employed a mixed methods
study combining a survey instrument (117 responses) and interviews (35) with
current and former undergraduate and graduate students who participated in five
programs through a physics and astronomy department at a large land-grant
university. To examine interviews, we employed a framework based on situated
learning theory, transformative learning theory, and the Dynamic Systems Model
of Role Identity. Our findings, based on self-reported data, show that students
who facilitated informal physics programs positively developed their physics
identity, experienced increased sense of belonging to the physics community,
and developed 21st century career skills. Specifically, students reported
positive benefits to their communication, teamwork and networking, and design
skills. The benefits of these programs can be achieved by departments of any
size without significant commitment of funds or changes to curriculum.
