I began writting a blog due to some courses I lectured in 2014 and 2015. In this blog you can find an initiation Arduino course and also an advanced course. It's used as reference in some Spanish institutes
The blog is published under CC license and you are free to use.
It's written in spanish, but if there is enough people interested I could translate.
URL: http://aprendiendoarduino.wordpress.com/
For any question, suggestion, improvement or contact me, please visit: Acerca de | Aprendiendo Arduino