TED-Ed
      An introduction to mathematical theorems - Scott Kennedy (2012x44)
      
      :  10, 2012
      Euclid of Alexandria revolutionized the way that mathematics is written, presented or thought about, and introduced the concept of mathematical proofs.  Discover what it takes to move from a loose theory or idea to a universally convincing proof. 
Lesson by Scott Kennedy, animation by Karrot Animation.