As indicated on a previous page, Peer-Reviewed Journals also include non-primary content. Primary research is what your professor probably wants you to use. Simply limiting your search results in a database to "peer-reviewed" will not retrieve a list of only primary research studies.
Learn to recognize the parts of a primary research study. Terminology will vary slightly from discipline to discipline and from journal to journal. However, there are common components to most research studies.
When you do a search in the database, find a promising article in your results list and then look at the record for that item (usually by clicking on the title). The full database record for an item usually includes an abstract or summary--sometimes prepared by the journal or database, but often written by the author(s) themselves. This will usually give a clear indication of whether the article is a primary study. For example, here is a full database record from a search for family violence and support in SocINDEX with Full Text:
Although the abstract often tells the story, you will need to actually look at (and read) the article to know for sure. So go to the article. Besides looking at the Abstract or Summary, look for the following components (Note: I am only capturing small segments for illustration):
Look for the word METHOD OR METHODOLOGY. The authors should explain how they conducted their research.
NOTE: Different Journals and Disciplines will use different terms to mean similar things. If instead of "Method" or "Methodology" you see a heading that says "Research Design" or "Data Collection," you have a similar indicator that the scholar-authors have done original research.
Look for the section called RESULTS. This details what the author(s) found out after conducting their research.
Charts, Tables, Graphs, Maps and other displays will help to summarize and present the findings of the research. (These will be much different than the kinds of tables and bright color photos seen in a popular magazine like Newsweek or a newspaper like USA Today.)
A Discussion indicates the significance of findings, acknowledges limitations of the research study, and suggests further research.
References, a Bibliography or List of Works Cited indicates a literature review and shows other studies and works that were consulted. DO USE THIS PART OF THE STUDY!! If you find one or two good recent studies, you can identify some important earlier studies simply by going through the bibliographies of those articles.
A FINAL NOTE: If you are ever unclear about whether a particular article is appropriate to use in your paper, it is best to show that article to your professor and discuss it with her or him. The professor is the final judge since s/he will be assigning your grade!