Tiering- "Tiering is a process of adjusting the 'degree of difficulty' of a question, task, or product to match a student's current readiness level. To tier an assignment, a teacher 1) determines what students should know, understand, and be able to do as a result of the task; 2) considers the readiness range of students relative to these goals; 3) develops or selects an activity that is interesting, requires high-level thought, and causes students to work with the specified knowledge, understanding, and skill; 4) determines the complexity level of that starting point task compared with the range of student readiness; 5) develops multiple versions of the task at different levels of difficulty, ensuring that all versions focus in the essential knowledge, understanding, and skill; and 6) assigns students to the various versions of the task at levels likely to provide attainable challenge. To guide development of multiple versions of the task, a teacher may refer to the continuums of the Equalizer (see Equalizer), use supporting materials that range from basic to advanced, provide forms of expression that range from very familiar to very unfamiliar, and relate the task to experiences that range from very familiar to very unfamiliar." (Tomlinson & Strickland, p. 358).
C. Tomlinson & C. Strickland (2005) Differentiation in Practice: A Resource Guide for Differentiating Curriculum Grades 9-12. ASCD.