Successful learning of an object-oriented programming style is greatly facilitated by a flexible, window-oriented interface and a “step-by-step” instructional methodology. Specifically, students can benefit from a learning sequence moving from working with object hierarchies to working with objects with behavior to more complex problems (conditional or sequential message passing, automation of behavior). Within each area in turn, a step-by-step approach of learning by conceptualization, learning by analogy, learning by experience, and learning by reinforcement is suggested. This is demonstrated using examples from the training of the KEE® Knowledge Engineering Environment™.