19yo male is brought into the emergency department by EMS after getting into an altercation and getting knocked unconscious.  He unsure of how long he was out, but he came to once EMS arrived.  He denies any nausea, vomiting, or vision changes.  He is drowsy/lethargic with his eyes closed, but is arousable to voice.  He can carry on a conversation, but he needs frequent redirection and he does not know where he is.  While talking with him, the nurse starts an IV and he tries to swat her away with his opposite hand.

What is the classic score we use and what is his score?

How good is it?

Are there any other scoring systems out there?