A year after 17-year-old Isaiah Laurencin fatally collapsed during a football practice, his family says they’re sure of one thing: Had Miramar High School coaches and staff acted differently, Isaiah would still be alive.

“My son should not be dead,” Isaiah’s mother, Angela Cooper, said Tuesday in announcing the family’s intention to sue the Broward school district. Under Florida law, people suing a school district must give six months notice, so the formal lawsuit — along with the actual amount of damages being sought — is still six months away.

The Broward school district, as is typical with expected litigation, declined to comment.

According to the Broward County medical examiner’s office, Isaiah died of cardiac arrest after participating in off-season conditioning drills at Miramar’s football field. The July 2011 death shocked his classmates, and the football team carried the weight of his death for the rest of the season. Miramar players made a habit of saying Isaiah’s nickname, “Zay,” just before breaking the huddle, and players would point to the sky in his honor before every snap of the ball.

What caused the sudden death? The medical examiner’s autopsy report cited multiple factors, including Isaiah’s weight (he was 6-foot-1 and 286 pounds), high temperatures during the football practice, and blood disorders suffered by Isaiah, including sickle-cell trait.

His family members, who say Isaiah had not been diagnosed with sickle-cell trait, complain that the autopsy report minimizes the errors made by school coaches. For one, the family notes that a year earlier, Isaiah had been hospitalized for heat stroke. That history of heat sensitivity should have been foremost in coaches’ minds, the family said.

“They just missed so many chances to save his life that day,” said the family’s attorney, Benjamin Crump. Crump, who also represents the family of slain Miami Gardens teenager Trayvon Martin, criticized Miramar coaches for taking too long to call 911, and for not immediately getting Isaiah into a cooling tub at the first sign of trouble.

“It was almost like ‘what not to do’ in this situation,” Crump said.