An amazing web-site with lots of electronics projects powered by learning platforms based on Arduino, and Rasberri pi.
Excerpt from web-site.
The Adafruit Learning System
In 2012, after years of coding tutorials by hand, Limor put together a small team to build a custom tutorial management system from the ground up. The Adafruit Learning System allows us to make a wide range of awesome tutorials fast and efficiently. We hope these tutorials will help you learn something new, and inspire you to make something great!