Often, the students who are reading a textbook are quite new to the field of study. They may be taking their first class in a particular discipline. If they are actually majoring in the subject matter, the book may still be used in a course that covers new ground.
An effective chapter introduction sets the stage for effective reading and learning. It introduces the chapter content in a way that makes it accessible to readers and gets their buy-in.
There are two methods of crafting a chapter introduction that are particularly effective for instructional purposes: