KB, can you tell me why the instructor recommended a -1.0 EV setting?
s/he is probably basing it off of an incomplete understanding of digital photography. The same advice used to be quite popular. See, if you blow out a photo, then that section of the photo is gone forever (no way to ever get detail into it). If you underexpose by a stop, then you can go into your favorite photo editing software and add brightnes into the picture.
However, this doesn't take into account two important aspects of digital photography. First, most digital cameras record a lot of noise in the darker sections of a photograph. As such, when you brighten the photo, you bring out this noise. Ick.
Second, digital cameras record the most detail and information in the lightest end of the spectrum. So, as a whole, when you underexpose your picture you give up detail.
If you want to be meticulous about it, and if your camera has a histogram setting (will display a histogram on the preview window after you take a shot), then always overexpose your photo to the point where the histogram isn't being cut off on the right (right is light, left is dark). You can then move the exposure down after the fact and your photo will really shine. Many cameras will also show blinking sections of the photo where it's blown out if the histogram is turned on.
Or, if you don't have the time, set your camera to exposure bracketing and just take three shots. Then pick the one that's not exploded out and call it good.