Stories of discovery and invention often begin with a problem that needs solving. Summoned by the king to investigate a suspicious goldsmith, the early Greek mathematician Archimedes stumbles on the principle that would make him famous.
For a full biography and interesting facts about Archimedes, visit this website: http://www.ancientgreece.com/s/People/Archimedes/
Here's a cool visiual of the Archimedes' Principle: http://physics.weber.edu/carroll/archimedes/principle.htm
This video explains in depth how to use Archimedes' Prinicple to solve a problem: http://www.sciencekids.co.nz/videos/physics/archimedesprinciple.html
Visit this site for everything you may want to know about Archimedes: https://www.cs.drexel.edu/~crorres/Archimedes/contents.html