Many how-to ' s on writing high school level papers advise students to use only "scholarly" sources, but often don't give guidelines for what that means. What is the difference between a scholarly source and one that is unacceptable for a high school level paper?
Scholarly sources are articles that have been peer reviewed. Peer review is a process by which all new material, as in the case of scientific discoveries, any ideas or implications are scrutinized and critiqued by experts in their field before they become widely accepted. As in the case of literary peer-review it means that the work is examined and evaluated with the view of publication in mind.
Articles from reputable encyclopedias, law books or dictionaries are also acceptable. These have usually been written by the experts in their respective fields.
Source material can also be found from International, US, state or county government documents.
Other acceptable sources for material that may not be officially "scholarly" but are suitable include newspaper, magazine, television or website articles.
Primary sources such as autobiographies, letters, emails, memoirs or blogs might also be sources for material. Interviews or survey results you have conducted yourself may also be used. You must be careful, however, to tell whether the source you are quoting could be biased, out-of-date or otherwise flawed. To help the student determine which sources are scholarly and which are not, I find it helpful to get them to write an annotated bibliography.
An annotated bibliography is a list of the sources used with a short description of why this source is reliable by giving a short bibliography of the writer's qualifications. It also states briefly what the article is about and why it is being used as a source in the student's paper. The length of these entries shouldn't be any longer than about 100-200 words, so each of these components must be no more than a sentence or two. Through writing this, you student must research the author of the source and find out how credible the writing is, and therefore he will be able to evaluate sources of information.
So, what sources are not appropriate? Wikipedia is the go-to source for a lot of students. It is good to get your students out of the habit of using it as a source for quotes. It is alright to use as an overview of the subject as a starting point for research and it is alright to use the sources it uses for a place to find some sources. But that is as far as your student should go with using Wikipedia. The same applies to other internet sites such as About.com and Ask.com.
This probably goes without saying, but other websites for students to avoid include any "cheater" sites offering to "write your essay for you" or any source that asks the student to pay to download it or asks for personal information from the student before he can access it.