A human tutor must have a plan of instruction, but be able to deviate from the plan when the student behavior calls for changes. This paper presents observations of human tutors and describes the FLOW tutor system, a computer-based simulation of a human tutor that is capable of giving advice to a student learning a simple computer language. The tutor has a schema-based knowledge structure containing information about the programing language, the student's instruction booklet, and the student's developing knowledge. These schemas form the basis of a distributed intelligence system which uses conceptually guided and data-driven processing to interpret the student's behavior, update the model of the student, and give advice to the student. (Author)