Your son has been having behavioral problems lately. He has not been completing his homework, he has been late to school, and he is having disciplinary problems at school and at home. He closes his door and withdraws from the family. You were thinking that this was just normal teenage angst that he was going through. One morning, while he is at school, you go into his room and see pieces of aluminum foil with burn marks on them. You also find several lighters inside his dresser drawer. You now suspect that he is using drugs.