• Codecademy – Online interactive platform that offers free coding classes in programming languages like Python, JavaScript, and Ruby, as well as markup languages including HTML and CSS. Gives your points and “level ups” like a video game, which is why I enjoyed doing classes here. Not lecture-oriented either; usually just jump right into coding, which works best for those that have trouble paying attention.
  • Coursera – Coursera partners with various universities and makes a few of their courses available online free for a large audience. Founded by computer science professors, so again a heavy CS emphasis.
  • Udacity – Outgrowth of free computer science classes offered in 2011 through Stanford University. Plans to offer more, but concentrated on computer science for now.
  • Physics Database – Dozens of free Maths and Science books available as PDFs.