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!
University of Arizona
The Biology Project: Human Biology
This site provides basic information on human genetics and reproduction using tutorials, simulations, images and quizzes. There are also links to other worthwhile sites.