We spent yesterday's class working very slowly through one genetics problem, and now I can't decide whether what we did was way too easy or too hard.
I wanted the students to appreciate how best to approach genetics problems. Normally this would be done in tutorials, but the university administration has decided that this course doesn't need tutorials (1500 first-year biology students! (not all mine)), so I did it in class. Using clickers makes this possible, because students are participating, not just watching.
The problem was a complex one. To solve it students needed to combine information from three different crosses, so we worked through each cross in turn, considering possible hypotheses and testing them against the data. I wanted to emphasize that doing the analysis slowly made the logical steps easier to appreciate, but I fear we went too slowly through the first parts. Almost every student got the PRS questions right, which indicates that we probably should have been spending less time on these issues. And we didn't really get to the last part of the problem, which is both the most difficult and the most rewarding - not getting to the answer leaves the students hanging, and leaves them with the most difficult part.
And, based on comments from students after class, most students will find finishing the problem harder than it should be because they missed the significance of information I gave them about why the problem would interest a scientist. They don't understand how two genes can both affect one phenotype, in this case that the genes each code for an enzyme that produces a pigment (pink and blue respectively) and that the pigments mix to produce the purple wildtype flower colour.
So I'm going to have to spend part of the next class providing this explanation, which means less time to spend on pedigrees and sex chromosomes and aneuploidy.