Charlie returns to the university to undergo more psychological tests, the most important of which involves completing a maze. When Charlie can't grasp how to solve a printed maze, researcher Burt Selden introduces him to Algernon, a white mouse that has been trained to run a model maze. Burt suggests that Charlie and Algernon "race" each other to see who can complete the maze first. Algernon repeatedly defeats Charlie, and Charlie is amazed that the mouse is so smart.
Charlie's inability to complete a paper maze further demonstrates his low mental ability. The fact that Charlie isn't upset or disturbed that he is less intelligent than a mouse suggests his limited emotional range.