Game-based learning not only contributes to a learning environment that is interesting and engaging for students but also fosters collaboration while meeting educational goals. Recognizing the potential of digital games to promote primary-source use for discovery and problem-solving, the Library of Congress established funding to advance the development of digital apps for a variety of grade levels. The KidCitizen project aims to develop a free cross-platform app that provides game-based learning activities with primary sources for K-5 students. KidCitizen's interdisciplinary team of historians, educators, child development specialists, and game designers are integrating the Inquiry Design Model with game-based learning approaches. The KidCitizen app, which will be accessible to teachers this spring, provides authentic, age appropriate interaction with primary-source materials, is guided by research-informed practices and evidence-based pedagogy, engages children in exploring civics and government concepts through historical sources, and helps them make connections with their daily lives.