In this analysis, we argue that science education should attend more deeply to youths' cultural resources and practices (e.g. material, social, and intellectual). Inherent in our argument is a call for revisiting conceptions of "prior knowledge" to theorize how people make sense of the complex ecologies of experience, ideas, and cultural practices that undergird any learning moment. We illustrate our argument using examples from the domain of personal health, chosen because of its tremendous societal impact and its significant areas of overlap with biology, chemistry, physics, and other scientific disciplines taught as core subjects in schools. Using data from a team ethnography of young people's science and technology learning across settings and over developmental timescales, we highlight two youths' experiences and understandings related to personal health, and how those experiences and understandings influenced the youths' sense-making about the natural world. We then discuss the implications of our argument for science education.