Why do i get this error (NoMethodError)

I am having a problem with my ruby on rails cloud 9 code while my task is to create an article from the UI and save it to the database when I hit submit.

This is my image of my problem: http://ift.tt/2fZaxx4

This is my cloud 9 code

routes.rb:

Rails.application.routes.draw do
# The priority is based upon order of creation: first created -> highest 
priority.
# See how all your routes lay out with "rake routes".

# You can have the root of your site routed with "root"
# root 'welcome#index'
resources :articles

root 'pages#home'
get 'about', to: 'pages#about'

Articles controller (articles_controller.rb):

class ArticlesController < ApplicationController
def new
@article = Article.new 
end
end 

new.html.erb in articles folder in views:

<h1>Create an article</h1>

<%= form_for @article do |f| %>

<p>
    <%= f.label :title %>
    <%= f.text_area :title %>

</p>

<% end %>

Article model (article.rb) :

class Article 

end

I have done a migration and this is my migrate file :

class CreateArticles < ActiveRecord::Migration
def change
@article = Article.new

create_table :articles do |t|
end
end
end