Finding stuff for free is going to be trouble, and I don't know many articles myself, but here are some ideas.
scholar.google.com
This is still in beta, so it doesn't work nearly as efficiently as regular google, but the idea is that it searches for literary/scientific journals and articles.
Wikipedia
Since you are a teacher, you probably hate this. But, I recommend you search through it to find what you are looking for, then scroll to the bottom of the article and see what sorts of references it uses. (Obviously you can do the same thing with any textbooks you happen to have on the subject.)
Online Archives
If you use the google option, you will probably come across a few articles from online scholarly archives. One such archive is:
http://www.jstor.org/
These usually require memberships, but if your school doesn't want to invest in books, getting a membership to a few online archives is a good alternative.