To Kelby Jasmon, there was only one answer. The question: If he received yet another concussion this football season, while playing offensive and defensive line for his high school in Springfield, Ill., would he tell a coach or trainer?

Jasmon, with his battering-ram, freshly buzz-cut head and eyes that danced with impending glory, immediately answered: “No chance. It’s not dangerous to play with a concussion. You’ve got to sacrifice for the sake of the team. The only way I come out is on a stretcher.”

Jasmon, a senior with three concussions on his résumé, looked at two teammates for support and unity. They said the same thing with the same certainty: They did not quite know what a concussion was, and would never tell their coaches if they believed they had sustained one.

Matt Selvaggio, who plays with Jasmon on both lines, said: “Our coaches would take us out in a second. So why would we tell them?”