Despite the fact that the majority of museum visitors are often very young children, much research in museums focuses on pre-teen learners (ages 8-12). Our goal in this study was to investigate the behaviors of children aged 5-8 during a visit to a science exhibition. We aim to develop a methodology to assess children's levels of engagement with the interactive exhibits and how the participation of explainers (mediation) affected this engagement. Our working hypothesis was that different activities (and different kinds of mediation) would generate different levels of engagement. We recorded videos from 13 groups of 5- to 8-year-old children visiting "Aventuras pelo corpo humano," an interactive exhibition about the human body. A large data set including thousands of excerpts of video-taped activity was analyzed using collaborative, online, qualitative data analysis software (Dedoose). The results suggest that the type of mediation overrides the design of the exhibition when it comes to children visitors' experiences and that, despite their emphasis on promoting visitor engagement, explainer mediation strategies often represented deficit and banking models of teaching and learning, highlighting the importance of training for explainers that goes beyond content training and focuses on strategies of mediation that promote learner agency and protagonism. This study confirms previous empirical insights, which can help guide the design of future exhibitions as well as professional development of explainers and science communicators.