During my B.Sc. days, Mrs. C from the Chemistry Department explained a single topic for an hour. Mrs. C was assigned Physical Chemistry for the 2nd and the 3rd Year (i don't remember which semesters, though). She was a little silly, i guess. We were to remember the three C's when in her class. One for Chemistry, C herself and the third being a calculator. Most times, we hardly carried a calculator, which was a necessity during Physical Chem classes.

She was annoyed the first few classes. But, it ceased afterwards. Her classes were fun.