On to the assignment:
Before our first field trip, I was fairly sure that in both hemispheres, water drains in a clockwise direction. My reason for thinking this, was based on the Simpson's episode when they go to Australia. If I remember correctly, Bart demonstrates that toilets flush in the opposite direction in Australia than they do in the Northern hemisphere. Assuming it was a joke, I remember looking that up afterwards and verifying that it wasn't true. But I apparently forgot HOW it wasn't true.
During the field trip, I was fairly certain that I saw the water draining counter-clockwise, but I doubted that perception. Partly because my classmates mostly saw a clockwise motion, and partly because it was just hard to tell from the angle I was looking.
After about 2 seconds of Googling (and several more minutes trying to find 'trusted' sources), I now know that the affect that started the myth of different drainage directions, the Coriolis affect, is not so strong that can affect plumbing. What does affect the direction is the shape of the basin, the motion that water is already going in (affected by how the water swirled on the way in, or by disturbing the water in some other way.
As for some trusted examples (I assumed that Snopes doesn't count), here are three websites from educational institutions that all debunk the sink/toilet Coriolis myth:
Penn State College of Earth and Mineral Sciences
From the website of Emeritus Professor of Meteorology, Alistair B. Fraser
From Cornell University's Curious about Astronomy question and answer site:
From am old page on the webstie of John Baez who is a Mathematical Physicist at University of California Riverside: