"In some Literature and Arts Cores, over 100 places often aren't used," she said.

For this reason, she said, students who plan not to use their lottery slot should contact the head TF for the course.

According to Elisabeth Swain '63, associate director of the Core Program, the organization of Shopping Week makes it difficult for professors to hire the correct number of teaching fellows and for administrators to place classes in rooms of the correct size.

"It's hard for us to project which classes will be 160 students and which will be 200," Swain said.

But Lewis said that despite the obvious organizational problems shopping week presents, the institution is valuable.

"One of the real strengths of Harvard is shopping," she said. "But there's an uncertainty that's hard on everybody--professors, teaching fellows, undergraduates.