Below please find links to archived Q&A discussion for the Introduction to Objects II course.
Exercise 4.1: It's All in the Genes
Exercise 4.2: Marching Penguins
Exercise 4.3: DRY Penguins
Exercise 4.4: Black (and White) Penguin Magic
Exercise 4.5: Penguins, Properties, and the Prototype
Exercise 4.6: Up the Food-I-mean-Prototype Chain