As the coach, you don't have to diagnose the concussion. Your job is to recognize a possible concussion by observing two things: (1) a blow to the head or body that is concerning and (2) any sign or symptom that tells you something may not be right with the athlete. Use the signs and symptoms information to assist or the CDC clipboard sticker. If you have a reasonable suspicion that these two indicators are present, follow the motto: When in doubt, sit them out. This means that if you suspect a concussion may have occurred, you should immediately pull the athlete out of practice/play, inform their parents about what happened, and direct the parents to information about concussions, and how to get medically evaluated.
A concussion is defined as a direct or indirect force to the head (could be a direct hit or a whiplash-type injury) that results in neurological impairment. If you see or are told that a child has received a blow, you should ask specific questions about their condition.