A device that can be used as a testing device can't be trusted by the student as an anonymous "poll taking device". Without this trust, any data obtained is invalid. Good randomized response techniques, used by statisticians, use a method that the the responder can trust and validate with his own knowledge so that the responder can really feel anonymous. An example of this is letting the person answer one of two questions, one non-sensitive and the other not. The person chooses which to answer based by the number that comes up on a pair of rolled dice, which the poll-taker can't see. If the odds aren't even, the statistician has the mathematical knowledge to estimate the answer if he uses a large enough sample. The person can test the dice, and can use his own observation to validate the method.