Two days into shopping period, three courses have potential enrollments of over 500 students on the Online Course Selection system, according to course demand data accessed at 11 p.m.

Leading the pack is, as we expected, “Introduction to the History of Art,” with 584 shoppers, while “Great Hoaxes and Fantasies in Archaeology” has 519 and “Philosophy and the Science of Human Nature” has 505.

Two other psychology courses are also in high demand: “Sex, Evolution, and Human Nature” has 485 shoppers, and “Drugs, Brain, and Behavior” has 300. Among economics offerings, “Financial Theory” has 355 shoppers, with introductory micro- and macroeconomics not far behind.

But shopping period holds surprises not only for lecture rooms you thought couldn’t be packed fuller, but also for small classes gaining more interest. The environmental studies course “Biotechnology and the Developing World” was an eight-person lecture last year, professor Anjelica Gonzalez said in an email to the News, but today nearly 100 students showed up — what Gonzalez called a “pleasant surprise.”

“I am only sorry that the assigned classroom was small, making it difficult to deliver the lecture, but I am working to make sure we are in a bigger room for Thursday’s class,” she wrote.