A principal’s attempts to improve the selective Bronx High School of Science by adding more tests, holding teachers to high standards, and streamlining syllabi is running into an unusual roadblock: a planned student protest that will liken her to a quacking duck.

Valerie Reidy this year asked teachers to standardize what they teach within each subject and to give diagnostic pre-tests, so that teachers could measure what students needed to learn. She also introduced a mandatory program focused on raising juniors’ scores on the PSAT.

Teacher complaints about testing are standard fare at schools nationwide, yet at Bronx Science students have also joined the fray, handing out articles and letters criticizing their principal and even forming a 376-member group on the social networking Web site Facebook to complain about her. “The majority of students hate the principal with a passion,” a junior, Michelle Rybak, said while hurrying to the subway after school the other day. She said she was rushing because she had to study for a math test — one of a growing number she takes each week. “We learn at the same pace, but they’re testing us more,” she said. “We’re studying constantly.” Ms. Reidy said the changes are meant to ensure that each of the school’s 2,700 students is learning, a process she called “individualizing instruction.”

“It’s a huge challenge,” she said. “But this is a goal that’s set by the Department of Education, and I think it’s a good one.”

A foreign language teacher who said she has taught at Bronx Science for 18 years, Marina Chudnovsky, said Ms. Reidy’s changes have “turned the school around.” “She is the best thing that could have ever happened to the school,” Ms. Chudnovsky said. “Everything is better, from academic achievement to air-conditioning.”

Ms. Reidy’s self-described “decisive” management style has angered other teachers and even generated blinking rebukes in a local newspaper. A teacher who quit abruptly last year, Bryan Sans, in a resignation letter he forwarded publicly, criticized Ms. Reidy for perpetuating a “culture of fear.”

A social studies teacher who is the school’s liaison to the teachers union, Robert Lang, said many other teachers have left the school or are considering leaving.

Ms. Reidy said 18 teachers who taught last year are no longer at the school this year. A Department of Education spokeswoman, Melody Meyer, said the rate was not unlike that of the past three years, when between 15 and 16 teachers left each year.

Ms. Reidy said that, aside from two teachers who were fired, no others left on bad terms last year. Several students said that was not the impression teachers gave them. “A lot of teachers have left because of how Ms. Reidy runs the school,” a 17-year-old senior, Sarah Sibug, said. She said some talented teachers were among those who left.

Channeling the student angst, a group of seniors recently turned an annual initiation ritual, Freshman Appreciation Day, into a protest against Ms. Reidy. Resuscitating a battle waged three years ago by a teacher who was eventually fired, students said they printed out stickers comparing their principal to a duck. “Quack,” they said. One of those students, who asked not to be named, said he is planning a second protest along the quack theme for next month.

The teacher who created the slogan, Robert Drake, said it is a criticism of an honorary degree that led Ms. Reidy to call herself wrongly a “doctor.” Ms. Reidy said she never called herself a doctor.

A 16-year-old junior of Queens, Carter Suryadevara, said he is happy to see his principal pushing for higher-standards. “You can’t blame the administration for cracking down. They have so many teachers that aren’t doing their job,” Mr. Suryadevara said. “Everyone’s against Ms. Reidy for no reason. She’s just protecting the school’s rep.”