Try the Universal Design tutorial online at the IDEA Center -- Designing Accessible Environments.
From the web site:
This course is designed to provide an introduction to the topic of accessibility, not a course on accessibility codes. We have included recommendations that go beyond the codes because research demonstrates their value. We also have not included every item found in codes to keep the length of the course manageable. Rather, the course focuses on giving the user basic knowledge of how to achieve accessibility, in a way that will satisfy most codes.
A companion booklet, A Primer on Accessible Design, is available to serve as a reference guide on the issues of accessibility. The computer aided instruction then provides the testing mechanism to evaluate what a user has learned, while reinforcing the lessons in the primer.
An online demonstration of the program is available.
Both the program and primer are available from the IDEA Center, and can be ordered through the Publications Order Page.