ABSTRACT
This is really a follow-up for the previous activity on flat vertex folds, but it doesn’t have to be. Students are given squares of paper with crease patterns drawn on them and asked to fold along the lines to fold the paper up into something flat. The catch is that the crease patterns are impossible to fold flat without inserting new creases. This is puzzling because each vertex will locally fold flat, but the global pattern will not. Students are asked to explain why these won’t fold up.
