The bloodied shoes that Brooke had worn the day of the shooting had been taken away as evidence. Her favorite sweater was also seized. Her black backpack now has a bullet hole in the bottom, from one of the AR-15 rifle rounds that filled her English class with a choking haze and killed Alex Schachter, Alyssa Alhadeff and Alaina before her eyes there in room 1216.

So on Wednesday, Brooke went back to school carrying little more than her phone and a small bracelet made by students that said “ALAINA.”

The shortened school day started with fourth period, the class where everything had shattered. For 30 minutes, the students reunited with the classmates and teachers who had huddled with them in closets and corners. They spent 24 minutes in each of their other classes and were done by 11:40 a.m. Robert W. Runcie, the Broward schools superintendent, said about 95 percent of the student body of 3,293 had returned.

There were extra counselors and therapy dogs on hand, and it will be days — if not weeks — before students return to their regular lessons. The school’s principal, Ty Thompson, said on Twitter that the focus of the week would be on healing, and classes are being dismissed at 11:40 a.m. for the rest of the week in an effort to let the students acclimate to being back.

“There is no need for backpacks,” he wrote. “Come ready to start the healing process and #RECLAIM THE NEST.”

Back at home that morning, it was 7:23. Time for Brooke to go.

“Are we ready?” Ms. Harrison asked.

“Yeah.”