When PATRICK COSTELLO first came to Stanford as an undergraduate, he had never done any computer science. But after taking CS 106A, an introductory course, he fell in love. In fact, as an undergraduate he joined the CS 198 section-leading program, which provides undergraduates with an opportunity to teach the introductory CS courses. Costello graduated in 2012 and is now working on his master’s in the School of Engineering. In this video, produced by another engineering student, MICHAEL WALKER, Costello talks about how he and computer science became a perfect match.