McDonald, John-2015-12-102015-12-1018-7-2006-http://dx.doi.org/10.2312/cgems04-11-1367Rotation matrices are one of the first topics covered in introductory graphics courses, and yet the details of arbitrary rotation matrices often get swept under the rug due to their complexity. This CGEM presents a direct, constructive derivation of the ma-trix for a rotation about an arbitrary axis, enhanced with animations that help build in-tuition for the calculation. The details of this derivation can be described in an intuitive manner that builds on the procedure for calculating the matrices for rotations about the coordinate axes. This treatment is suitable for use as a handout for students to use as a supplement to the usual course text.Animation 3DLinear algebra3D animationFundamentalsMathematics10.2312/cgems04-11-1367John McDonald-Animation 3D, Linear algebra, 3D animation, Fundamentals: Mathematics