Plataforma de Aprendizagem de Programação on-line

Code School

http://www.codeschool.com/

CodePupil

http://codepupil.com/

CodeRace

http://coderace.me

CodeAcademy

http://www.codecademy.com/#!/exercises/2

TryRuby

http://tryruby.org/levels/1/challenges/0

TheCodePlayer

http://thecodeplayer.com/

CodeAvenger

http://www.codeavengers.com/

Mozilla Develop

https://developer.mozilla.org/en-US/learn

RubyMonk
http://rubymonk.com/

CodingBat
http://codingbat.com/