Increasingly school districts are attempting to align curricula, assessments and standards, in an effort to eliminate inequities. Some approaches like Prek-3 initiatives call for coordination of instruction between preschool and later elementary grades that would resemble a coherent instructional system with clear learning goals for students aligned to supports for teachers to help them to teach in, possibly new, ways that would realise such goals. Central to these efforts are instructional materials like curricula that specify learning goals used to teach the students and the guide teachers. Districts seeking to coordinate prek with elementary must create novel solutions for coordinating supports for teaching that is connected across prek and elementary classrooms. In this study, we consider the mandated math curricula that two school districts in California used to establish district-wide prek-3 programs. What emerged from our analyses of curricula were distinct designs for continuity of instruction across grades: one district's curricula offered consistently challenging tasks across grades, while the other emphasised easy tasks for younger students followed by increasing levels of challenge for advanced grades. We argue that prek-3 initiatives present a unique opportunity to recognise why continuity of instruction specified by curricula matters as much, if not more, than coherence or alignment when districts seek to coordinate and connect instruction in preschool and elementary classrooms. (author abstract)