Abstract: A person's mastery of a body of knowledge is determined by having the person write objective questions for a test that is given to a group of test takers. The results of the test are then analyzed to determine how well the person's questions discriminated between those who did well on the test and those who did poorly. The better the questions discriminate, the more mastery the person has of the body of knowledge. In a learning situation, a cycle of study, writing questions, analyzing the results, and determining mastery may be repeated until the desired degree of mastery is reached. The technique may be used for individuals or groups and both the question writers and the test takers may work in teams. Question writers may also be test takers, and the evaluation of a question writer may reflect both the extent to which his or her questions discriminate and his or her performance on the test.