The Recipe Book You Have to Slice Open

The Bogotá Escuela de Cocina Carulla cooking school in Columbia have a great idea for helping students practice their knife skills with the recipe book you actually have to slice open.
Called Slice a Recipe, the book features thin lines down the sides that ask users to take a knife and slowly cut through.
Slice through the book in certain parts then reveals individual recipes.  The idea, on top of great marketing of course, was to help students at the school practice their knife skills by giving them a reward when they cut precisely.
The book was create by the ad agency Ogilvy & Mather.