Being out of print does not mean that a book is no longer protected by copyright. Fair dealing for educational use allows making copies of "short excerpts," and other educational exceptions in the Copyright Act allow other specific uses; see the Guide for Teaching & Copyright at MRU for copying guidelines for classroom use. If a longer portion is required and the book is still protected by copyright, you should contact the publisher to request permission to use the material. 

The Copyright Clearance Fund may be able to support payment of copyright license fees for this copying.