CS1 curriculum is inspired by a highly successful Intro Computing course (15-112, Fundamentals of Programming and Computer Science) that has been taught at Carnegie Mellon University for the past 10+ years. It is predicated on the notion that learning about programming and computer science should be fun and engaging. This requires interesting problems to solve, as computational problem-solving is the core of computer science. It is why we choose to first expose students to graphical problems in CS1: they are visually engaging, allow for multiple correct solutions, and provide visual cues when a solution goes awry.
Reference Material
Unit Review Videos and Documents