Essential Principles of Economics: A Hypermedia Text (Roger McCain)
This text, by Roger McCain of Drexel University, covers both micro and
macro. It includes questions to test student's understanding. As one
would expect, it also includes links to explain concepts. It perhaps
takes a somewhat broader approach than many principles texts.
http://william-king.www.drexel.edu/top/prin/txt/EcoToC.html