Es gratis, tiene muchos, muchos cursos desde cero.

What I love most about the Khan Academy videos is that they are freely accessible and have content that is varied for age level and subject areas. They even have videos that focus on Pixar animation that my daughter has watched multiple times just for fun.

I like that Khan academy offers free resources and that the site is comprehensive and easy to navigate. With a little exploring on the site you can learn just about anything!