If you’re still working on the systems courses, I used http://www.smartcockpit.com when I was testing the original incarnation of the academy. Unfortunately, the site seems to have removed most of their resources but thanks the Wayback Machine (web.archive.org), I have found access to it all.
http://web.archive.org/web/20120506012641/http://www.smartcockpit.com/plane/boeing/B737/