The Hourglass

A strange camp counselor works at a Young Pioneer camp — in the morning he is kind, but by evening he is terribly angry. All the children knew about this peculiarity of his, and so they allowed themselves to fool around only in the first half of the day, while by evening they walked the line. And no one would ever have found out what was going on if one day the curious boy Petya had not peeped at dawn through the half-open door of the counselor's room...