I particularly dislike the rude interuption of watches that beep every hour. I expect you to consider carefully all absences from chemistry class. Remember that field trips are not counted as absences. You are required to complete you work before the field trip or to have all assignments ready when you return to class. If you miss one or more classes before a test, you are still required to take the test the day you return to class from the field trip.
Chemical knowledge is cumulative.
Participation in today's chemistry activities is often essential to understanding tomorrow's work. Classwork that is done out of order is often less meaningful to students. Some assignments and opportunities are almost meaningless out of context and out of order. Missed work is difficult to master on your own. Chemistry knowledge and understanding is more than a list of completed assignments and tests.