“They say it out loud — ‘So what?’” Ms. Leong said. “‘My mother just kicked me out. Kick me out, too? Go right ahead.’”

Ms. Leong said it was usually more effective to talk with students than to suspend them. “Taking ownership and apologizing and ‘what am I going to do different’ is different for them, and I think they learn to respect that,” she said.

As the year went on, Lieutenant Cleare continued to emphasize that students could change their relationship with the police by extending some basic courtesy. And he offered his own friendship. He cheered on the basketball team at its championship game in February, and in May he challenged the players to a game at the Coney Island Y.M.C.A. against him and a group of fellow officers. The students won both games. He attended graduation in June, and in August he helped Ms. Leong organize what she called a unity barbecue at the school for current students and recent graduates, their families and officers from the 60th Precinct and PSA 1.

If the goal of the Junior Citizens Police Academy was to change the dynamic between the students and the police, it did not work miracles or magically erase a legacy of distrust. Many of the students remained wary of the police and still believed that many officers were racist. But they had developed, in many cases for the first time, a close relationship with a police officer, as well as some respect for the challenges of policing and the risks officers take to protect the public. Bobby and Jahkhil both became interested in law enforcement as a career, which in turn sharpened their interest in college as a necessary step on that path.

Often, what Lieutenant Cleare said in class discussions mattered less than that he was there at all. Jonathan, 19, who grew up in Coney Island with Bobby and, like him, transferred to Liberation from Lincoln, said the basketball game against the officers had affected his feelings about the police more than anything in the class had.

“I could tell they had love for the game, like I do,” he said. He added that even though he never confided in Lieutenant Cleare about something deeply personal, he now felt that he could.

Lieutenant Cleare said the class had affected him, too. “It actually just gave me more insight to the struggle that our kids face — the real struggle that they have being in an urban community,” he said.