Why are the continents "drifting"?

Watch the video(s) of your choice (or all of them!) to answer the questions below.  Make sure to copy the questions and answer in complete sentences. 

1.  What is the theory of continental drift?
2.  Provide at least 3 pieces of evidence that support Alfred Wegner's theory of continental drift.
3.  What is the theory of plate tectonics?
4.  Review: What is the lithosphere? 
5.  Review: What is the asthenosphere?  
6.  What is the force behind plate tectonics (moving plates)?
7.  How does the relationship between temperature and density play a role in the theory of plate tectonics?

Learn more here: http://education.nationalgeographic.com/education/encyclopedia/continental-drift/?ar_a=1 if you would prefer to read!