I found a 3" x 3" piece of tinfoil outside my son's window. It is scarred with a one inch square patch of burnt residue in the center and there are about 15 tiny punctures under that. He has a drug use history though we believed it was only pot and he has recently passed a drug screening at his school to indicate "for certain(?)" that he has stopped that. I suspect meth for a number of other reasons and have a million questions, but I guess the most pressing ones are: 1. Is tinfoil used in this way for meth or could it be for crack or something else? 2. How savvy are kids concerning things like school drug tests - would he be able to find out what is tested for and what is not and/or if he is doing meth/crack is there a way for him to beat a "hair clipping" test? I am distraught and would appreciate any help that you can offer.