>> Alpha students, explained co-author Piech, moved efficiently from one point to another as they wrote code, creating a streamlined program. Beta and gamma stu

>> Alpha students, explained co-author Piech, moved efficiently from one point to another as they wrote code, creating a streamlined program. Beta and gamma students, on the other hand, wrote themselves into so-called “sink states” in which their programs slammed into dead ends from which they had to back out before they could resume progress. Very interesting, and intuitively right to me. The difference is likely in the ability to create and maintain a consistent mental model of the program's structure and behavior during the implementation.