For one thing, I knew how to use the periodic guide in 6th grade. For another, does one need a masters in library science to know how to do this? Couldn't the clerk from borders just get a few hours of training on the Periodic Guide?
That's nice for you. Not everybody learns that stuff in 6th grade, and most of the people that did learn it learned from a librarian. Problem with the idea of a few hours of training is that the periodic guide is one of dozens of reference books librarians use on a regular basis, nobody is going to put a minimum wage employee through two weeks of training on reference guides which won't even be useful to them (since Borders doesn't store microfiche of past issues, or most of the books that are in a library, that kind of information woun't do you any good at Borders).