SIX FILMS WERE DEVELOPED TO TEACH VISUALIZATION IN THREE DIMENSIONS FOR ENGINEERING GRAPHICS OR DESCRIPTIVE GEOMETRY COURSES. THE FILMS UTILIZED A "THOUGHT MODEL METHOD" WHICH HAD BEEN USED FOR OVER A DECADE BY THE INVESTIGATOR. THE METHOD CONSISTED OF TRACING IN THE AIR AND DESCRIBING RELATED POINTS, LINES, PLANES, AND SURFACES BY THE USE OF THE HANDS. THIS CONSTRUCTION OF IMAGINARY FIGURES WAS ACCOMPANIED BY VERBAL DESCRIPTION, AND THE ORTHOGONAL REPRESENTATION OF THESE FIGURES WAS MADE ON THE BLACKBOARD. THE TWO-DIMENSIONAL REPRESENTATION WAS MADE ONLY AFTER THE STUDENT HAD THE EXPERIENCE OF SEEING AND MANIPULATING THE VISUALIZED THREE-DIMENSIONAL PROBLEM. THE FIRST FILM WAS SHOWN ONLY TO TEACHERS TO FAMILIARIZE THEM WITH THE METHOD. USE OF THE REMAINING FIVE FILMS WAS COMPARED TO LIVE USE OF THE METHOD AND TO CONVENTIONAL INSTRUCTION IN A STUDY INVOLVING 358 COLLEGE STUDENTS TAKING DESCRIPTIVE GEOMETRY. IT WAS FOUND THAT THE THOUGHT MODEL METHOD COULD BE LEARNED AND USED EFFECTIVELY BY TEACHERS OF ENGINEERING GRAPHICS TO BRING ABOUT IMPROVEMENT IN CLASSROOM PERFORMANCE. (JM)