The world of ‘test preparation’ is very different from the world of ‘regular study’, with those engaged in ‘regular study’ being people who may read just for the joy of reading. Off hand, I do not know anyone who takes tests for the joy of taking tests! :-)
I would like to illustrate how different these realms of study can be by elucidating a sliding scale of “seven stages of understanding”...
1. Which tutor has the best credentials for the services that I am looking for?
a. Can the tutor present information successfully?
b. Does the tutor understand how to provide high-quality educational services to the student, the parents, or the educational system as a whole?
You can check out http://ocw.mit.edu/index.htm
You can also check out other MOOCs like Coursera, or Kahn Academy.
Also, if you are looking for free study materials in Physics, check out http://www.staff.science.uu.nl/~hooft101/theorist.html