Understanding include and extend in Ruby

I was watching a presentation by Dave Thomas called, "MetaProgramming - Extending Ruby for Fun and Profit", and realized that my understanding of include and extend is mixed up.

My Wrong Understanding
I thought "extend" will add methods from a module into a class as instance methods and "include" will add them as class methods.

Correct Understand:
"extend" adds methods from a module into a class as class methods.
"include" adds methods from a module into a class as instance methods.

It is quite easy to demonstrate this actually.

module SomeModule
  def hi
    puts "hello"
  end
end

class ExtendSample
  extend SomeModule
end

ExtendSample.hi

class IncludeSample
  include SomeModule
end

IncludeSample.new.hi