ABSTRACT
Summary This activity takes the following approach to modeling paper folding: When we fold a piece of paper flat, we’re really reflecting one part of the paper onto the other. Thus, every time we make a flat fold, we’re performing a reflection. Reflections of the plane can be modeled with matrices. So, students are given a simple, four-valent flat vertex fold and asked to compute the 2 × 2 reflection matrices for each of the crease lines. Then, they are asked what they get when they multiply these matrices together. Does it make sense that we get the identity?
