This is an example of how to include both class methods and instance variables by including a module into a class.

module_class.rb

require 'active_support/concern'

module Testable
  extend ActiveSupport::Concern

  def instance_puts
    puts "This is an instance method"
  end

  # def self.included(base)
  #   base.extend(ClassMethods)
  # end

  included do
    self.extend(ClassMethods)
  end

  module ClassMethods
    def class_puts
      puts "This is a class method"
    end
  end

end

class History
  include Testable
end

History.new.instance_puts
History.class_puts