What type of student will bravely call attention to his own ignorance when the question is posed to a class: "Does everyone understand?" Interestingly enough, it was a student who suggested that those who do respond comprehend most of the concept, lesson, problem, etc., and need only a minor point made clear. Others, whose lack of understanding is more comprehensive, whose confusion is more widespread, may be too intimidated to call attention in such a public way to their situation. Often, the latter are so confused that they cannot think of questions to ask. Yet these are the students who most need assistance. How can instructors determine what it is they do and do not understand?