Heads Up: Concussion in High School Sports is a great resource from the CDC (Centers for Disease Control) for coaches, parents, teachers, and athletes.
The site has posters, reference sheets, pocket cards, videos, training materials, and more, all to increase the awareness of concussions and how dangerous they are. The site and materials are meant to help prevent concussions from going unnoticed and leading to serious consequences.
All the materials are free to order and many are available as a free download.
As a paramedic, I've treated dozens of high school students with concussions. Many where allowed to play even after showing symptoms. This is extremely dangerous and can lead to permanent brain damage, disability, and death.
Share this information with all of the coaches, athletes, parents and faculty in your building or district and help keep our student athletes safe.
There is also a site for younger athletes: Heads Up: Concussion in Youth Sports.