Although the person who creates a work holds the copyright, there are rights that can be exerted by others when they want to use or copy part of a copyrighted work. Some of the exceptions that pertain to education and teaching are:
Fair Use is a set of exceptions provided within the copyright law, allowing others to use a copyrighted work without permission, if their use falls within the exception's guidelines.
There are four factors that are considered when looking at the fair use exceptions. However, not all four have to be met in order for the fair use argument to be used and meeting one of the factors isn't necessarily considered conclusive. All four factors should be considered.
Purpose:
Nature:
Amount:
Effect:
As an example, anything used when teaching a class is probably an educational use, which is one of the four factors. However, that doesn't mean that a court would rule favorably in every single case that involved teaching; the other factors also play a part.
The difficult aspect of fair use is that there is no hard and fast way to know if your use is a fair use; that can only be decided by litigation. All four of these factors need to be considered when trying to decide if a use might be considered a fair use.
Was the use transformative or a direct copy? There is more leeway for a transformative use, such as a parody or mash up, than for a direct copy of a piece of work. A good example of this is the Andy Warhol Campbell Soup can paintings; while they directly copied the cans, their transformation is what made the copy allowable.
Was the amount used reasonable or was it the entire work or the "essence" of the work? Did the use have an effect on the market for the item? Was the work used fiction or non-fiction? Courts tend to look more favorably at allowing the exemption if the item was nonfiction. For example, copying part of a newspaper story vs. using part of a novel.