Modules and Classes, Includes and Extends

[Alpha Blue]

I wanted to provide an example which for me is easier to understand than
always using the Foo + Bar examples others use. When using modules and
classes, I see them as containers. I decided to just put together a
more far-fetched example using the Earth, Gravity, Oxygen, and an
AlienSpecies.

http://gist.github.com/290785

I don't normally nest modules and classes deeply, so I'm just trying to
wrap my head around the idea of including and extending modules and
classes.

I believe that I'm correct with the very last example, or am I not?

If you want to add some more examples to this, please do.