This academic year, Lewis said, there were four minor fights, mostly involving shoving and pushing. He said that no one was injured but that all eight students were forced out for violating the nonviolence pledge they signed when they were admitted.

In at least one case, Lewis said, he had not wanted to make the student leave but believed he needed to show that the school was serious about enforcing its rules.

If he had made an exception, Lewis said, "I believe it's over, and everything that I've said was a lie."

He said that there were no student assaults on staff at Shoemaker this year and that he could not imagine any of his students hitting an adult.

"We were supposed to be one of the most violent schools in Philadelphia," he said. "All I know is we have the same children, and these children are not violent. They're very intelligent. They are talented. And their families have been unbelievably supportive."

Most parents appreciate the strictness.

"You have to abide by their rules," said Marvin Robinson, whose daughter Cinquetta, 16, was promoted to ninth grade. "They don't play. They don't take no nonsense. They are about teaching the kids."

That firmness was evident even at the eighth-grade promotion. More than 80 students will move to ninth grade, but only 56 participated in the ceremony. The others, Lewis said, had missed mandatory rehearsals.

Although results of this year's state tests will not be available until later this summer, Lewis said teachers were encouraged by the students' performance on the school's own benchmark tests.

And the Shoemaker building is halfway through its own physical renovation, which includes huge new windows, bright hallways, colorful linoleum, and splashes of vibrant paint on the walls.

"We have known in [educational psychology] for many years that the color of rooms really does stimulate learning," said Lewis, who joined Mastery last year after seven years as a principal.

The students love the colorful surroundings, but they talk more about the safer atmosphere at Shoemaker, the help and attention they received from teachers, and the personal changes they experienced this academic year.

Eighth grader Aja Waters, 14, said she began the year "out of control," as she had been in seventh grade at Shoemaker. She was suspended in December after being disrespectful to teachers.

During the suspension, Waters did some thinking and decided she wanted to make a better life for herself.

"When I came back, I just changed my whole way of thinking," she said. "I have been getting my grades up. The teachers are giving me good phone calls at home, saying how much I improved."

Khalif Younger, 14, changed, too.

He had gotten into trouble regularly in seventh grade at Sulzberger Middle School in West Philadelphia and had a rough time at first at Shoemaker.

He was suspended twice for cutting up on a corner near Shoemaker with friends and darting into traffic after school.

"It's called 'disrupting the community,' " Younger explained. "But I changed my behavior and my attitude, and it's much better."