Justin Pollina gazed around Southern Regional High School’s main gymnasium, his classmates gathered in bunches, laughing and hugging, taking selfies or simply chatting amongst themselves. At one point, he had to pause because he couldn’t speak without choking up.

“We have a lot of great kids in this class. So many of us are going to be lifelong friends because of all we’ve been through together,” said Pollina, who was fortunate enough to experience graduation on the same day as his 18th…