Abstract: What! You haven't ever seen a Whippo? What about a Whammel? Well, how do you think that whales evolved? Which mammals do you think are their closest living relatives? Trying to make sense of whale evolution is a great place to engage in some evolutionary reasoning and look closely at the way scientists work through difficult historical problems. By the way, the term Whippo is used as a sort of shorthand for the hypothesis that whale and hippos represent sister groups—that is, they are each other's closest living relatives. This problem space provides a collection of resources for going beyond the discussions of whale evolution presented in biology textbooks to look at how different types of data can be used to resolve this set of phylogenetic puzzles and to explore other related questions.