A student's choice of an answer to a test question is a coarse measure of his knowledge about the subject matter of the question. Much finer measurement might be achieved if the student were asked to estimate, for each possible answer, the probability that it is the correct one. Such a procedure could yield two classes of benefits: (a) students could learn the language of numerical probability and use it to communicate uncertainty, and (b) the learning of other subjects could be facilitated. This report describes the rationale underlying a procedure for eliciting personal estimates of probabilities utilizing a proper scoring rule, and illustrates some new techniques for calibrating those probabilities and providing better feedback to students learning to assess uncertainty. In addition, new results are presented comparing the incentive for study, rehearsal, and practice provided by the proper scoring rule with that provided by the simple choice procedure, and concerning the potential effect of cutoff scores and prizes upon student behavior. (Author)