Scholarly or peer-reviewed journal articles are written by scholars or professionals who are experts in their fields. In the sciences and social sciences, they often publish research results.
Substantive news articles are reliable sources of information on events and issues of public concern.
Popular articles reflect the tastes of the general public and are often meant as entertainment.
Sensational intend to arouse strong curiosity, interest, or reaction. They are not factually accurate.
Keeping these definitions in mind, and realizing that none of the lines drawn between types of journals can ever be totally clear cut, the general criteria are as follows.
There are a couple of ways you can tell if a journal is peer-reviewed:
You've been asked to find at least one primary research articles. Primary sources in this case:
You may also choose to use some secondary sources (summaries or interpretations of original research) such as books (find these through the library catalog) or review articles (articles which organize and critically analyze the research of others on a topic). These secondary sources are often useful and easier-to-read summaries of research in an area. Additionally, you can use the listed references to find useful primary research articles.