A primary source is a document or physical object which was written or created during the time under study, and present during an experience or time period and offers an inside view of a particular event.
In science, primary literature is the original publication of a scientist's new data, results, and theories.
A rule of thumb for evaluating whether or not a scientific article is a primary source is that it has a "Materials and Methods" section. If it has such a section, it is primary. If you are assigned to get a few primary articles, that will probably work for you.
Journal articles may be primary literature, there are many articles published which are not primary literature, particularly review articles, which do not report new findings but review known data.
Some websites constitute primary literature (here, here and here, for example) which include credible primary data. Note "primary" is not an indicator of the quality of the item (see Retraction Watch); for that we use peer reviewed, and to a lessor extent, the designation academic / scholarly.
Secondary literature includes review articles (which include reviews of the literature) textbooks, and most scholarly or academic books (that repeat information that is already published). The vast majority of popular periodical publications (magazines, trade journals, newspapers) are usually considered tertiary literature, in that they are repeating information that has already been published and they are usually written for a non-technical audience .
Note that the vast majority of empirical articles (a term used in Education and Social Sciences) are probably primary literature, but not all empirical articles are primary.
Types of primary sources include:
Search by keyword for Primary Sources in the Library Catalog to find direct references to primary source material.
Perform a keyword search for your topic and add one of the words below: (these are examples of words that would identify a source as primary)
Primary research presents original research methods or findings for the first time.
Secondary research does not present new research but provides a compilation or evaluation of previously presented material.
If one of the experts interviewed in the Mother Jones article published a study in JAMA (The Journal of the American Medical Association) documenting for the first time the effect that handguns have on youth mortality rates, only the JAMA article would be considered primary research.