A short time before final exams you lose your class notes. You recall having seen them four days ago. Use your own personal activities and movements during the past four days as the basis for formulating your hypotheses as to the whereabouts of the notes.

For each of the following situations, invent at least three hypotheses aimed at explaining what went wrong or at solving the problem. Then, for each hypothesis, describe one or more experiments or inquiries that would confirm or disconfirm the hypothesis.