Scenario 1: A teacher took copies from the internet for a class assignment.
Yes, this teacher should be allowed to due so for education purposes and it is a fair usage. This is copyright infringement.
Scenario 1: A 14 year old girl wanted to earn more money for a brand new bicycle. She resales her latest CD's of Bruno Mars on Amazon.
Yes, the girl is allowed to resale her CD's of Bruno Mars because she had purchased it so its hers. This is copyright infringement.
Fair use is like a way of saying you have the right to claim the copyright infringement. Unless, you claimed that you made the Justin Timberlake CD then, you broke the law. You stole someone's work and that's not fair use. When you publish a work on the internet typically, you would were "Copyright Infringement" meaning you don't owe the company or product but you had either purchased it and wanted to share your opinion on it. Criticism is someone's opinion, but don't troll about it.
Shepard Fairey begged to be guilty in February for destroying documents. He was fined for $25,000 back 2009. He was charged for using the image under the fair use doctrine. According to a statement by the U.S. attorney for the Southern District in New York. The concept of a copyright allowing reproductions in specific instances of news reporting and other situations.
Halloween before image used with permission, creative commons.

