Joel VanderWerf wrote:
> ---
> module Operations
>   def add(x,y)
>     x+y
>   end
> end
> 
> include Operations
> 
> p Operations.add(1,3)
> ---

Oops. This code works, but it's a little confusing. Since I included 
Operations, all I needed to do was

p add(1,3)

If I hadn't included Operations, then

p Operations.add(1,3)

would _not_ work, because add is an instance method, not a module 
method, of Operations.

Now I've probably only increased the confusion. There are better 
explanations in the Pick Axe book:

http://www.ruby-doc.org/docs/ProgrammingRuby