Ralph Taylor. Taylor is one of the most outstanding research scholars in the field of education in the United States and even the world, and a famous American curriculum theorist. Taylor put forward the basic procedures, steps and methods of curriculum development, that is, Taylor principle (target mode). Taylor principle consists of two closely related basic principles: one is the principle of curriculum preparation; The other is "the principle of evaluating activities". Taylor believes that the most useful form of goal statement is behavioral goal, that is, to state a special learning result with observable student behavior. He believes that goal is the core of curriculum development and is called "the father of behavioral goal".