Do not question pupils in public as to whether or not they have done a
certain misdeed. Simply keep a closer watch than before. Look at no one
in particular, but lift your eyes a little above the heads of the
pupils, so that you can watch what is going on without seeming to do so,
and let your face show neither anger nor annoyance. Do not accuse
anyone. Even after you think you know who is guilty, do not say you
know; on the other hand, do not suggest in any way that you are not
sure. If you are sure that a certain pupil is guilty, ask him to see you
a moment after school. Then talk with him in a friendly way, smiling
frequently, so he will be in the mood to confess. When he does confess,
thank him for his admission and tell him you know he will not bother you
any more. Treat him kindly after the interview.