While some students learn regardless of the instruction and some students learn adequately with whole group “one-size-fits-all” instruction, most students benefit from a highly skilled teacher and an environment that carefully attends to individual student differences. Teachers who want to maximize each student's potential have to respond to differences by developing a differentiated classroom environment. The teacher must have clarity about the learning goals, use assessment information to make instructional decisions and provide engaging and challenging work that is matched to a learner’s needs. Differentiated instruction is an observable, classroom level practice that uses assessment information to monitor students’ rate of progress and level of performance over time in order to make data-based decisions. This formative use of assessment to meet students’ needs is also an inherent component of Florida’s Response to Intervention (RtI) framework. This module is an introduction to some of the basic guidelines of differentiation.