My understanding of this topic:
An Acceptable Use Policy (AUP) is a kind of legal policy that stipulates how a piece of technology can be used. For example it might be unacceptable to create or transmit offensive or obscene images. In the high school setting it would be more likely address issues of personal safety. But in the business world it takes the form of a Terms of Service document, which states how users can interact. It basically protects the owners of business, schools, or website owners from harmful legal action.

Educational example of this topic:
An Example of an Acceptable Use Policy.
An Example of how to construct an Acceptable Use Policy.
This video is an example teaching method to instruct students on AUPs.


Media support:
This video is an example AUP for a High school.


Learn more here:
http://whatis.techtarget.com/definition/acceptable-use-policy-AUP