I got a D in a highschool Biology Genetics Lab working with Fruit Flies because our Chi Squared p-value was a little less than the common significance value of 0.05.

Our results were close enough that we could still easily determine the phenotype and genotype of the parent and grandparent Fruit Flies (red/black eyes), but it was kind of a bummer to be punished in a highly error prone experiment (flies dying from too much ether, flies flying away, flies getting stuck in food and dying, etc).

It did teach me to be more careful when running experiments but I probably would have given myself a C, not a D