<p>Humans reason implicitly and explicitly about the physical world, which enables them to successfully interact with and manipulate objects in their environment. This reasoning is studied under different names across three main literatures: education, developmental psychology and cognitive science. At a high level, education researchers examine the acquisition of formal scientific knowledge, developmental psychologists explore children’s emerging understanding of their physical surroundings and cognitive scientists analyse the structure of the mind. These different disciplines have reached divergent conclusions about what children and adults know about ‘cognitive mechanics’ and developed parallel scientific theories of these phenomena. In this Review, we describe the findings of these three literatures and conclude that each literature contributes robust and reliable findings that must be taken seriously even when they seem to be contradictory. We suggest that further progress requires reconciling these literatures; one avenue is to consider multiple interlocking cognitive mechanisms that are differentially engaged across scenarios and across development. Finally, we outline a research programme to further reconcile these literatures.</p>