Have you been to a school recently? The "resource officer" is present in any secondary school that can afford him. This personification of the fear and incompetence of the modern American educator is the reason that fistfights, smoking, possession of prescribed medicine, etc. now regularly result in children holding criminal records. The American public high school is quite explicitly an arm of the law enforcement-industrial complex.
The likelihood that a survey in which an American public school student admitted drug use would not find its way into the grubby clutches of law enforcement is approximately nil.
5th amendment jurisprudence requires the threat of criminal proceedings to be real, not baseless speculation ("The likelihood that a survey in which an American public school student admitted drug use would not find its way into the grubby clutches of law enforcement is approximately nil.")
Stipulating your claim (are you a jurist?), how does this shake out? Do you expect the likelihood of referral to law enforcement/prosecution to be zero? If it is non-zero, how do you expect the set of self-incriminating surveys to be partitioned? Is it possible that the school administrator will consider the wealth of a student's parents, and their propensity to seek redress through the representation of an attorney? This would make these surveys more troubling, not less, because now they're putting just the poor kids into "real, not baseless" criminal proceedings.
The likelihood that a survey in which an American public school student admitted drug use would not find its way into the grubby clutches of law enforcement is approximately nil.