ActiveModel::MassAssignmentSecurity::Error: Can't mass-assign protected attributes:

I am following along the tutorial Ruby on Rail 3 Essential Training from Lynda.com. I am having a difficult time creating an Active Record Entry. This is the error I get in my console. ``` 1.9.3p125 :007 > user = User.new(:first_name => "Mike", :last_name => "Jones") ActiveModel::MassAssignmentSecurity::Error: Can't mass-assign protected attributes: first_name, last_name from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activemodel-3.2.3/lib/active_model/mass_assignment_security/sanitizer.rb:48:in `process_removed_attributes' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activemodel-3.2.3/lib/active_model/mass_assignment_security/sanitizer.rb:20:in `debug_protected_attribute_removal' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activemodel-3.2.3/lib/active_model/mass_assignment_security/sanitizer.rb:12:in `sanitize' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activemodel-3.2.3/lib/active_model/mass_assignment_security.rb:230:in `sanitize_for_mass_assignment' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.3/lib/active_record/attribute_assignment.rb:75:in `assign_attributes' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.3/lib/active_record/base.rb:498:in `initialize' from (irb):7:in `new' from (irb):7 from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.3/lib/rails/commands/console.rb:47:in `start' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.3/lib/rails/commands/console.rb:8:in `start' from /home/mark/.rvm/gems/ruby-1.9.3-p125/gems/railties-3.2.3/lib/rails/commands.rb:41:in `<top (required)>' from script/rails:6:in `require' from script/rails:6:in `<main>` ``` This is what I have in my Model: ``` class User < ActiveRecord::Base attr_accessible :first_name, :last_name end ``` What am I doing wrong. I have rails 3.2.3