From the library home page, click the tab "Article Quick Search" (for help navigating Article Quick Search see the video tutorial on the "Find Research" page in this guide).
At the left of the results page, click peer reviewed, as below:
As you can see from the screenshot, the results page contains a lot of information about the articles listed.
What is NOT Peer Reviewed?
open web pages
most newspapers, newsletters, and news items in journals
letters to the editor
columns and blogs
preprints and e-prints
anything in a popular magazine (e.g., Time, Newsweek, Glamour, Men's Health)
Some sources which are not peer reviewed are still trustworthy. Websites produced by well known entities, such as state and federal government, America Cancer Society, Smithsonian, National Center for Education Research, (a government body), Education Weekly, are reliable.
A rule of thumb if a source is unknown, is to discover who produces it, and everything you can about that person or institution.