It is easier to gain early admission to Harvard College than get into a class with Harry Potter on the syllabus.

While Harvard College admitted 18 percent of its early applicants in December, Professor Maria Tatar only admitted 10.5 percent of interested students to her class Folklore and Mythology 90i: “Fairy Tales and Fantasy Literature.”

After pre-term planning failed to accurately predict student interest in some courses, many undergraduates found themselves facing competitive lotteries with low acceptance rates in several popular classes.

Although 180 students expressed interest in Folklore and Mythology 90i when they submitted their non-binding course selections in November, about 300 students showed up for the course’s first lecture on Wednesday. Only 32 students were accepted into the course late Wednesday night.

After years of teaching the class in a large lecture format, Tatar is teaching it as a small seminar this semester, in part because only one graduate student applied to be a teaching fellow for the course.

Pre-term planning estimates led professors Douglas A. Melton and Michael J. Sandel to hire nine teaching fellows for their course Government 1093/Life Sciences 60: “Ethics, Biotechnology, and the Future of Human Nature.” They expected about 135 students, Melton said.

When about 600 students showed up at Sever 113, Sandel and Melton moved the first lecture to Sanders Theatre. The professors then tried to permanently move the class to Sanders in order to accommodate all interested students, but their request was not approved, forcing them to whittle the crowd down by lottery to the roughly 300 students who would fit in Emerson 105.

Stephanie H. Kenen, administrative director of the Program in General Education, attributed professors’ inability to accommodate high percentages of interested students in a number of classes to a lack of classroom space and qualified teaching fellows.

“Funding is not a factor. If there are qualified people available to teach, we will pay for them,” Kenen wrote in an email, adding that “it can be challenging to go from a course of 100 to one with 400 students quickly and still preserve the quality of the instruction in the course.”

Pre-term planning also underestimated student interest in U.S. and the World 18: “Thinking about the Constitution,” indicating that 53 students planned to enroll in University Professor Lawrence H. Tribe’s undergraduate course. This week, 157 students entered the online lottery for the course.

But the lottery for Tribe’s class proved less competitive than others, leaving only 6.4 percent of students without a spot when the lottery closed early Thursday afternoon.

Gen Ed courses are lotteried by the Program for General Education using a randomized process. Although Kenen said that the program “strongly encourages faculty to lottery randomly, regardless of class year, previous lottery status, etc.,” many professors said they took other factors into consideration.

In choosing students from the lottery for Folklore and Mythology 90i, Tatar and her teaching fellow selected students who had been kept out of previous incarnations of the course by a lottery in past years and gave priority to several Folklore and Mythology concentrators who needed the course to fulfill a requirement.

In narrowing down the pool for their bioethics class, Melton and Sandel gave preference to juniors and seniors and to those who had already taken Sandel’s popular course Ethical Reasoning 22: “Justice.”

Preceptor in Expository Writing Elise R. Morrison gave half of the spots for Expository Writing 40: “Public Speaking Practicum,” to seniors and then divided the remaining 15 spots among freshmen, sophomores, and juniors, aiming for a “gender balance and for fairly even representation across the disciplines (humanities, social sciences, sciences).”