This document discusses the three key elements - know, understand, and be able to do - that should be the focus when differentiating curriculum. It defines each element and provides examples. Know refers to basic facts and vocabulary that students should memorize. Understand focuses on major concepts and making meaningful connections. Be able to do outlines skills students should develop, including thinking skills, social skills, and skills related to independent learning. The document emphasizes that differentiation requires continually asking questions about what students should know, understand, and be able to do, as well as how they will learn and demonstrate their knowledge.