Students begin addressing some of the issues that arose in Lesson 2 by investigating the shape of a pop-up before and after the book is closed for the first time. They discover that a pop-up mechanism forces a fold to be made at a specific location in the pop-up piece.
For each student:
Scissors and tape
Ball-point pens and rulers, for making sharp folds. The pens don’t have to write.
Outcome: The book will make a fold in the pop-up. From an edge view, the strip will look like an arch before the book is closed, and like a triangle after the book is closed and then opened completely.