You will encounter many types of articles and it is important to distinguish between these different categories of scholarly literature. Keep in mind the following definitions.
Peer-reviewed (or refereed): Refers to articles that have undergone a rigorous review process, often including revisions to the original manuscript, by peers in their discipline, before publication in a scholarly journal. This can include empirical studies, review articles, meta-analyses among others.
Empirical study (or primary article): An empirical study is one that aims to gain new knowledge on a topic through direct or indirect observation and research. These include quantitative or qualitative data and analysis. In science, an empirical article will often include the following sections: Introduction, Methods, Results, and Discussion.
Review article: In the scientific literature, this is a type of article that provides a synthesis of existing research on a particular topic. These are useful when you want to get an idea of a body of research that you are not yet familiar with. It differs from a systematic review in that it does not aim to capture ALL of the research on a particular topic.
Systematic review: This is a methodical and thorough literature review focused on a particular research question. It's aim is to identify and synthesize all of the scholarly research on a particular topic in an unbiased, reproducible way to provide evidence for practice and policy-making. It may involve a meta-analysis (see below).
Meta-analysis: This is a type of research study that combines or contrasts data from different independent studies in a new analysis in order to strengthen the understanding of a particular topic. There are many methods, some complex, applied to performing this type of analysis.
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.
Additional resources for evaluating the information that you find
1) Is the sample size appropriate? Was a control group used? Were the presented data statistically treated? Were the experiments well standardized? In summary: Were the experiments carried out according to the scientific method?
2) Were the conclusions derived from the results of the reported experiments?
3) Were statements not based on experiments supported by scientific article references?
4) Is the abstract appropriate? Does the title describe the article content?
5) Were the keywords well selected?
6) Are the references current?
7) Was the research subject relevant from either the social or academic viewpoint?
8) Does the article contribute new information or does it repeat what is known?
From De Avila, P., & Torres, B. B. (2010). Introducing undergraduate students to science. Biochemistry and Molecular Biology Education, 38(2), 70-78.