if i was to learn about Arduino and teach someone at the same time, i would definitly use Ladyada's tutorials.
You can find them here: Arduino Tutorial - Learn electronics and microcontrollers using Arduino!
Currently she has 5 lessons, and all the lessons start with a very very detailed list of every single component needed, complete with pictures and all.
The lessons are also very detailed with step by step instructions, pictures, explonations, and even little quizzes to see if you have understood everything.
MikMo