Great idea! I'd love to see the "interactive" side of your idea. For me the coolest thing about starting to learn coding was writing a line, running the app and seeing something output to the screen.

Also what helped me learn was having a mentor who would answer questions and push me to keep learning. I learned a lot mostly from books and working on things I wanted to build. However I recently went through Rails for Zombies and really enjoyed the interactivity of it.

Just thought of a silly but perhaps useful feature... (And assuming this is all done on the website) At the end of each tutorial ask them to write out a commit command. Get them used to version control (Git would be great).

Good luck!