“While it is clearly important to have specified learning targets for teachers and students, when we assume that all students reach their maximum respective potential if they achieve the same goals under the same circumstances on the same day, we operate in direct contradiction to all that we know about human development.” (page 35)
(Emphasis is mine)
Tomlinson, Carol Ann and Imbeau, Marcia B (2010). Learning and Managing a Differentiated Classroom. Alexandria, VA: ASCD.