The Flipped Science Fair (FSF) transforms the traditional science fair format by having middle-school students judge the research of early career scientists. At the FSF, students learn about cutting-edge research in a small group setting, with opportunities to ask questions and participate in hands-on demonstrations. By placing the students in the role of the "judge," the event gives students the opportunity to engage with scientists interactively and with authority. The FSF also provides science communication training for the presenting scientists. Leading up to the event, the presenters attend three workshops focused on distilling their research message to a middle-school level. The FSF effectively promoted science engagement by middle school students who expressed increased interest in science after the event. Moreover, presenters reported an improvement in their science communication skills to a broad audience and increased confidence during public speaking. Our partnership with Pathways to Science, Yale's coordinated STEM outreach infrastructure, enables us to measure the FSF's effectiveness long term, since the Pathways program tracks student trajectories through their college education. The success of the FSF led to the organization of satellite and virtual events, which provided more opportunities for public engagement and gave presenters additional chances to share their research.