A 90-minute computer-assisted instruction (CAI) unit course supplemented by a 1-hour lecture on the dynamic nature of three-dimensional rotations and Euler angles was given to 29 undergraduate engineering students. The area of Euler angles was selected because it is essential to problem-working in three-dimensional rotations of a rigid body, yet it has been a stumbling block to students in dynamics. Euler agnles are difficult to visualize and have mathematical properties which are unfamiliar to most undergraduates. Graphic presentations and the branching capabilities of CAI were used to combat these learning difficulties. The CAI program contained three problems in ascending order of difficulty, designed to link the physical geometry of the problem situation with the vector equation derived in class lecture. Although the final problem was typical of previous homework problems, students indicated that they did not consider the question difficult. In addition, students indicated that they considered the CAI program an interesting and effective teaching aid. (Author/JY)