The Pencil Book was the name given by Columbia students to the printed edition of the Directory of Classes. Printed in magazine form on cheap newsprint, the 'pencil book' earned its name because students could underline classes they were interested in registering for in pencil.
The University attempted to kill off the pencil book in 2000, citing it as an unnecessary expense, but efforts by the student councils preserved the pencil for another few years. The University eventually stopped printing the books in the early 2000s. Today, the only remaining references to the one-time fixture of campus life are the occasional web links to the Directory of Courses website.