This thesis discusses the design and development of a set of PLATO lessons for geometric modeling addressed for upper-level engineering college students, graduates, and the people engaged in related fields who received B.S. degree credit. Six PLATO lessons dealing with introduction to the methods of approach with curves, Bezier curves, B-spline curves, ruled (or lofted) surfaces, generalized blended surface, and B-spline surface are designed and developed. Five of them,except for the lesson for generalized blended surface, are prepared on line. They are programmed in TUTOR language in PLATO computer-based education system at KAIST which uses CYBER 174 computer as host. They are intended to be used, as PAL (PLATO Assisted Learning) lessons, in a multimedia PLM (PLATO Learning Management) courseware that uses text, filmstrips, and PAL lessons as its instructional media.