CHICAGO  The bonding moment between Veronica Tinajero and the student she calls Big Sunshine came during one of their first meetings.

“Have you ever been shot?” the student, a high school senior, asked. When Ms. Tinajero replied no, he looked genuinely amazed and said, “Wow, almost everybody I know’s been shot.” Later, he ticked off a list of his own bullet wounds: upper thigh, left hand, scalp.

“I should have been dead already,” he said.

With that, Ms. Tinajero, 24 and a public schools employee, gained a fuller understanding of what she was up against. A professional advocate, she is in Big Sunshine’s life for two reasons: to help keep him alive and on track to graduation, and now college. She is part of an ambitious but untested project born of crisis, a project that may take on added significance after a Supreme Court ruling on Monday that appeared to doom Chicago’s ban on handguns.

Last school year, 258 public school students were shot in Chicago, 32 fatally, on their way to or from school, traveling through gang-infested territory and narcotics wars on the South and West Sides. In an effort to get ahead of the next killings, the schools conducted an analysis to identify the 250 students most at risk of being shot (by studying profiles of 500 recent victims). Since December, each of those students has had an advocate like Ms. Tinajero on call to offer caretaking and support 24 hours a day, seven days a week.