We did not have to go back many generations. It was basically to see how dominant and recessive traits were expressed through a couple of generations. We also had to, based on what we figured our genotype to be, add a future spouse to our tree with the opposite genotype to ours and determine the probability of having children with certain phenotypes. It was a fine assignment in an era when stable families were more the norm. What I found funny was that my dad, whose parents had died years before, could not remember their eye color, which is a trait I always notice!
my niece did this homework during a Family gathering last Christmas, all measurements and observations were done of those present, and vague recollections of those who where not. It actually lead to several hours of fun family stories and memories!