ABSTRACT
In this chapter the author focuses on some exercises involving a prism. The beauty of doing concrete exercises is that they're real activities in themselves; they can be examined and interrogated in detail. The use of the prism, the first set of exercises, and the law of the fundamental hexagon come from Dusan Bjelic's paper "An Ethnomethodological Clarification of Husserl's Concepts of 'Regressive Inquiry' and 'Galilean Physics' by Means of Discovering Praxioms," Human Studies 18, 189-225. Some preparation is needed before starting the prism exercises. First, people need to have a prism. It can't be any prism; it must be an equal angled prism with a slanted face. They need to have sheets of plain white paper of a decent size, a ruler or straightedge to draw a short straight line, and a pencil and an eraser. They also need cross-hatched paper.
