The magnetic tape recorder has made it possible for those who train teachers to offer something more than verbal criticism of the lessons they supervise. Students may now be given the opportunity to hear themselves in action, study the methods they have used in handling different pieces of material and estimate for themselves the degree of success they have achieved in establishing a good working relationship with their pupils in a particular lesson. Such recordings—whether they are made in schools with classes of children or in a training department with groups of students playing the roles of children—can be of inestimable advantage to a student. But tapes are expensive and have to be used again and again. Many a recorded lesson which a tutor would gladly preserve for future reference, perhaps for comparison with later lessons given by the same student, must be erased to make room for another. Verbatim transcriptions can be made only at a heavy cost in time and energy, unless skilled shorthand-typists are constantly available for this purpose.