At basketball practice, your players are reassembling after a short water break. As Greg attempts to leap off the bleachers, his foot slips and he lands hard on the floor. However, you don't see this happen; you only hear the loud "thud" and see him lying on his back.
Your initial evaluation indicates that Greg is barely conscious, his eyes rolling randomly. You send for help and begin the primary survey. When you ask him if he can speak, he completely loses consciousness.