Mendel's rules are the based on simplifying assumptions--the genes being considered are in unrelated places in the genome, that they live on 'generic' nuclear chromosomes, and that gene products under study have no interaction with each other. What happens when one or more of these assumptions are invalid? Using a hypothetical organism (hey--the truth is out there, but it isn't very tractable!) you'll learn how to recognize and distinguish between these sorts of misbehaviors.

MendelStar

Recommended reading:
Mendel's 1865 paper on pea genetics. It's thoughtful, clearly written, and better science than 95% of the junk in circulation today. Start at
Electronic Scholarly Publishing
Click on the AUTHOR (with notes) link on the left, then find Mendel. You're looking for 'Experiments in Plant Hybridization'; I found the English version more approachable than the original, but then I don't know German...

NDSU site with some stuff that you may find useful

Some information about statistical testing: chi square