A new book by a New York City Teaching Fellows dropout raises questions about recent changes in the public schools — in particular, the alternative certification program the author quit.

The author, Dan Brown, joined the Department of Education program, which pulls high-achieving young people and career-changers into public schools for two-year teaching stints, in 2003. His “The Great Expectations School,” which is climbing the sales charts, recounts why he quit after just one year, a resignation following what he describes as so much stress that he had to begin taking medication to stave off premature hair loss. His book also raises questions about how he might have been persuaded to stay.

“It’s an excellent idea, to take altruistic-minded people and direct their energy and passion into an important public service,” Mr. Brown told The New York Sun. “Before you become a teacher in a high-needs area, though, you need more preparation.”

The fellows program, launched in 2000, was modeled on Teach For America, a nonprofit that recruits college graduates into a national “teacher corps.” Now the nation’s largest alternative certification program — 20,000 applicants applied for 2,000 spots in the 2007 class— the Teaching Fellows program to date has brought in more than 12,000 teachers to the city schools, according to the education department.

Yet education department data show that turnover is high for the fellows program, as it is in inner-city schools across the country. About 10% of each cohort of fellows do not last a full year. Just 42% of teachers who entered in September 2000 are still teaching in city schools this fall.

Mr. Brown said he believes a major factor is inadequate preparation. Rather than the traditional regimen of a full-time, multi-year program that includes time spent assisting a professional teacher, Teaching Fellows get just seven weeks’ preparation during the summer before they become official.

Mr. Brown called his experience “triage.” One lesson, he said, was: “Don’t smile for the first several months of school.” Another instructed him to post a public schedule of what would be taught each day.

None of this, he writes, helped him understand how to keep his rotating roster of 26 (and sometimes more) fourth-graders from throwing their chairs, punching each other in the face, and throwing frequent tantrums.

At one point he portrays himself as so at sea that he turns to journalist Ron Suskind’s biography of a former U.S. treasury secretary, “The Price of Loyalty,” for management ideas. “What would Paul O’Neill do?” he asks himself about his classroom.

The department’s executive director of teacher recruitment and quality, Vicki Bernstein, said she would be happy to follow Mr. Brown’s suggestion and extend the pre-preparation period to as long as six months, but called such an extension “prohibitively” expensive. She also pointed to an August study showing that the fellows on average have stronger test scores and prior experience than traditionally certified New York City teachers.

Mr. Brown said he has not given up on teaching. He is now enrolled at Columbia University’s Teachers College, studying to teach high school English. He hopes to teach in New York City public schools.