The chromatic aberration of lenses is a popular topic in introductory astronomy 1-4 and physics and is readily demonstrated on an optical bench to several students at a time. However, we are not aware of any published descriptions of demonstrations showing chromatic aberration that are useful for large lecture classes. This note describes a simple method of using an overhead projector and an extra lens for displaying chromatic aberrations in large lecture halls so it can be viewed by large audiences.