A number of interactive questions are embedded within the short film The Making of the Fittest: Evolving Switches, Evolving Bodies, which illustrates how mutations in gene regulatory regions can result in the evolution of major anatomical features.

Many freshwater populations of stickleback fish lack the long spines that project from the pelvis of their marine relatives. These spines are important in the ocean for fending off large predators, so why were they lost in freshwater populations? The film tells the story of how David Kingsley, Michael Bell, and other scientists have identified key genes and genetic switches responsible for the evolution of this remarkable body transformation. Scientists have even documented similar evolutionary changes that occurred in the past, by studying a remarkable fossil record from the site of what was an ancient lake ten million years ago.

This version of the film with embedded questions contains automatic pause points, during which students answer questions about the film to assess their understanding of the concepts presented. After answering all the questions, students can view and print their answers.