All is Fair with Fair Use

Fair Use encompasses the "how to's" and "for what's" for educational multimedia usage as a teacher, or a student.  The definition is hereby "a legal principle that defines the limitations on exclusive rights of copyright holders."  Let's take a closer look at the grit of this description.  By "a legal principle" I would think of a dogma, or doctrine that sets an important note or ideology into stone, that by which is enforced to any that may contend with such principle.  This outlines or "defines" the boundaries or "limitations" contenders are to adhere to.  "Exclusive rights" I take to mean as freedoms or privileges to the demographic the guidelines are designed for, this being the "copyright holders" whom are the creators or originators of the content and media.  As a teacher or student abiding by this statement, it is important to be aware of not just limitations, but pivotally, privileges and benefits of using worldly media within one's own work.  There is a fine line between plagiarism and purposeful usage.  It is purposeful if it shares a point to be made which is to be decided by the individual enacting Fair Use.
 For example, if I were sharing political cartoons and irony with a class to make a point and make the concept more interesting, I would use a famous Bill Waterson's strip:

Ha Ha Ha....

To use this, as Waterson's original creation, I would have to note that it is copyrighted and that I did not make this comic strip.  It is as simple as that.  I have the right, and fair use to use it.  How does this particular example comply with Copyright law?  Well, laws are dynamic in nature when onset with a challenge.  Challenges are due to change of social or political relations and objectives.  So law and challenges are interdependent.
         A. Does it impact the future of creative development?  Yes, it's a comic, and everyone loves a Calvin.
         B. Does it relate to personal ethics?  Yes, in the matters of truth as a a political play on words.
         C. Social modeling?  Sure, maybe negatively though in that we shouldn't knock people's teeth out.
         D. Potential embarrassment?  (Reread the comic.  Pay specific attention to the last box.)
Fair Use can be fun, if we search for ways to use it with a purpose.  By exploring various multimedia projects to use as classroom teachers to enhance how we teach and affect our students, we are also expanding our own creative bubbles.  The cool thing is, these bubbles never seem to pop.
Portion limitations when using other artists' work is that a "reasonable amount of copyrighted work can be used in a project regardless of the original medium from which the copyrighted works are taken."  This to me is saying to use whatever you want, or whatever you deem necessary.  Showing all three extended editions of Lord of the Rings Trilogy to your class in order to show the types of fictional characters that exist ie. elves, wizards, and hobbits... etc. might be a little excessive.  But showing a good thirty minutes of Tolkien's magnum opus would suffice to get that point across.  Best advice, is to stay updated on the laws, as they DO change.  Go out there and use material!  And lastly trust your own knowledge, or gut, in the matter.  If it seems to risky, refrain.  PANE: Purpose, Amount, Nature, Effect.

Extra: In regards to what Schugar was mentioning about music impacting music impacting music as a cycle, here is a Q&A with hip-hop artists on Fair Use in music culture at World's Fair Use Day.
http://www.youtube.com/watch?v=4_T9RgpUR_c