<p>Teaching, learning and wider educational systems entail complex activities. Claiming that a set of detailed prescriptions based on selective principles from educational sciences is all that is required to be effective, is simplism, it misunderstands the nature of that complexity. However, policies and practices can be, and are being enacted which require greater prescription and more structured universal programmes than we have had in Aotearoa New Zealand. Under some conditions, these may provide needed resources, but they carry significant risks for meeting our excellence and equity goals. This paper discusses the nature of the complexity and what educational sciences indicate about principles underlying effective teaching, learning and system change. It outlines the risks in simplifying and prescribing, and what enables innovation and flexibility with that complexity. Our phenomena are not like ‘rocket science’ and certainly not simpler, although some policies and practices can make what we do a limited form of technical expertise. </p>