University of Arizona
University of Arizona: Blood Types Tutorial
This site from the University of Arizona describes how blood type is passed on from parent to child. The tutorial covers the genetics of the ABO blood groups as well as Rh factor. There are even practice problems and blood type calculators!
Palomar Community College District
Flashcards for Human Blood Typing
These cards provide a quick, interactive review of ABO, Rh blood typing science. Good for test preparation.