“A common calculus exercise is to present a function and have students plot its graph,” explains Croatian math and computer science teacher Maja Cvitkovic. “But this is too passive for me.” To help students gain greater insight into functions and their corresponding graphs, Cvitkovic turned the traditional exercise “upside down,” as she describes it. Her students began by envisioning an image and then were asked to find the function that would create that image when applied to a list of random dots.