application_model.rb

require 'feedable.rb'
class ApplicationModel < ActiveRecord::Base
  extend Feedable
end

feedable.rb

module Feedable
  def act_as_feedable
    send :extend, ClassMethods
  end

  module ClassMethods
    def feed(last)
      self.where("created_at < ? ", last).order('created_at desc').limit(5)
    end
  end
end

gistfile1.txt

class Verso < ApplicationModel
  act_as_feedable
end