An Intelligent Tutoring System.
Albert T. Corbett · 1988
An Intelligent Tutoring System The course description would catch the eye of any undergraduate: Essentially no lectures. Class attendance required only one every two weeks. Learn on your own time. Schedule quizzes when you feel ready. The self-paced LISP programming course, offered as part of a research project in Carnegie-Mellon's psychology department, attracts about 150 students a year. But the bet news is that the course can almost guarantee success. In the most recent term, for example, students averaged 84 percent on quizzes and exams. Of course, self-paced courses are not uncommon. What is unusual about this one is that each is provided with a personal tutor to help with his or her LISP programming exercises. As the works step-by-step through the code for a given exercise, the tutor lets the know about any mistakes and tries to correct the misconception that caused the error. Also, at any point the requests, the tutor will provide a hint about the current goal or an explanation of how to accomplish it. This assistance is not provided by a human tutor but by a software program called the LISP Intelligent Tutoring System (LISPITS). LISPITS was developed at Carnegie-Mellon by John Anderson and a team of researchers. Its purpose is to provide some of the benefits of a human tutor. The program is based on state-of-the-art research where the fields of psychology and computer science intersect. Initially, research in human learning and problem-solving led to a theory about how skill knowledge is represented in memory and how that knowledge is learned and used. Subsequently, artificial techniques were employed to build a computer model of skilled performance in a specific task: LISP programming. Finally, this ideal student model was incorporated into a tutoring system, where it is used to evaluate students' performance. Tutorial Principles--Using the Tutor LISPITS has been designed to provide assistance in the context of problem-solving. After reading a section of text, the performs programming exercises at a computer terminal, and LISPITS provides guidance at two levels. It helps the work through the code for each exercise and tailors the exercise sequence to the student's performance. While the types LISP code, the tutor monitors it on what is essentially a word-by-word basis. As long as the is typing code that will work, teh tutor remains in the background; but if the makes a mistake, the tutor immediately interrupts to note the error and, if possible, diagnose and correct the conceptual error that the is most likely making. Then the is allowed to try again. In addition, the tutor has some special features to keep the from floundering. If, at a given point in the code, the either repeats the same type of error several times or makes a couple of mistakes that the tutor cannot diagnose, the tutor will simply provide the correct next step and an explanation, under the assumption that the is lost. As already mentioned, the tutor is capable of providing a hint about the current goal or an explanation of the correct next step whenever the requests. After the exercise is completed, the tutor evaluates the current state of the student's knowledge and decides whether he or she should practice some similar exercises before moving on to new concepts. Student Modeling--How the Tutor Works LISPITS is characterized as an intelligent computer tutor because it contains the knowledge required to solve the exercises along with the students. This knowledge, referred to as the idea student model, consists of approximately 500 IF-THEN rules for writing LISP code. These rules are not problem-specific; rather, they are a set of general rules sufficient for coding the exercises in the first 12 chapters of the course's introductory LISP text. …