The Educator’s Guide to Copyright, Fair Use, Creative Commons by Sue Waters and Ronnie Burt is a very comprehensive guide to what resources may be legally used in all types of publications. I have shared information on copyright and creative commons in the past but this post is particularly succinct and easy to understand.
Silvia Rosenthal Tolisano otherwise known as Langwitches is a great source for information and ideas for using technology in the classroom. She has created a flow chart that clarifies what materials are copyrighted and what materials are available for students and teachers to use. Langwitches Copyright Flowchart