Abstract
Fostering engagement and persistence in science, technology, engineering, and mathematics (STEM) among adolescents is critical for preparing future professionals in a rapidly evolving technological landscape. This study evaluated the impact of the Youth Development Program (YDP 2025), a cross-cultural STEM initiative involving high-achieving middle and high school students from the United States (n = 21) and South Korea (n = 13). The program provided immersive experiences, including mentorship, collaborative projects, research presentations, coding challenges and robotics workshops, and interactions with leading scientists, including Nobel Laureates. A mixed-methods approach was employed to examine program outcomes. Quantitative measures assessed students' STEM affinity before and after the program using Likert-scale surveys, analyzed with descriptive statistics and Welch's t-tests; effect sizes were calculated to estimate the magnitude of change. Unequal pre- and post-survey response rates limited the feasibility of paired analyses. Qualitative data from open-ended post-survey responses were analyzed thematically to capture participants' perceptions of learning outcomes, confidence, and future STEM aspirations. Results indicated minimal overall change in STEM affinity. U.S. students demonstrated a moderate increase (Cohen's d = 0.55), while Korean students showed little improvement. However, qualitative findings revealed substantial gains in practical skills (robotics programming, coding challenge, oral research presentations), confidence in STEM tasks, and motivation toward STEM careers. Participants emphasized mentorship, hands-on activities, and exposure to STEM professionals as particularly influential. Findings suggest that experiential STEM programs can enhance skills, confidence, and career-oriented motivation. Future iterations should expand hands-on challenges, integrate structured career exploration, and address language accessibility to maximize impact.