To address disparity issues in STEM fields, this study implemented a culturally relevant, hands-on learning program tailored for African American high school students from low-income areas in America's Deep South. The program included a one-month summer academy followed by a four-month collaborative app design project using MIT App Inventor. A mixed-methods evaluation was conducted with 22 participants, utilizing focus group interviews, pre- and post-surveys, field notes, and process documents to assess the impact of the collaborative app design experiences. The findings indicated improvements in participants' technical skills, time management, and collaboration abilities, as well as a positive impact on their computer science (CS) identity and interest in CS. However, some participants reported stress and uncertainty regarding pursuing future careers in CS, underscoring the need for ongoing and tailored support. These results suggest that culturally relevant, hands-on learning experiences could play a vital role in increasing African American students' engagement and interest in STEM fields.