1. Consider why the scientific "climate" had changed by 1900 so that three botanists rediscovered Mendel's ignored work.
2. Determine if other genes might have multiple alleles.
3. Consider polygenic inheritance and how it affects the expression of such traits as height, skin color, intelligence, etc. Cover the idea of a normal distribution, and consider what kind of offspring two very tall individuals would have, for example. You might talk about the regression to the mean and why two very tall individuals would be likely to have children closer to the average height.
4. Talk about the mechanisms of interaction between
the environment and the genotype to produce the phenotype. Students
often don't realize that the phenotype can change over time, as
when hair changes from blonde in childhood, to dark in the adult,
to white in the older person, even though the genes remain basically
the same. Also consider that there are some changes in the genotype
(e.g., producing cancer) as a person ages.