A high school girl, mid-teens, goes to an unchaperoned party in which she's been warned that some of the kids there will be using cocaine.
She herself, has no experience with drugs.
She has some experience with kids who drink alcohol and some who smoke joints, but none that she is aware of who use cocaine.
Without seeing anyone actually using cocaine, how is she to recognize that someone at the party is high on it? Are there symptoms to look for? If so, do the symptoms differ from alcohol or marijuana use?