Many models of planning and lesson construction in the United States advocate an objective-driven approach whereby teachers create performance-based goals that their students should accomplish by the end of the lesson. Teachers then evaluate lessons by determining if students have accomplished these objectives. Often, this model of planning focuses only on the acquisition of content as determined by summative assessment. "Summative assessment," usually occurring at the end of a lesson, is primarily used to determine mastery as compared to "formative assessment," which usually occurs throughout a lesson to provide ongoing feedback regarding teaching and learning. This article describes a planning framework that considers both math content and student context for teachers who design mathematics lessons. The model incorporates both formative and summative assessment, and instructional decisions are based on student needs. This model is informed by the planning practices of early childhood educators in Reggio Emilia, Italy, in addition to the principles of teaching mathematics outlined by the National Council of Teachers of Mathematics (NCTM). (Contains 1 figure.)