Peer-reviewed journal articles have gone through a special review process (peer review, naturally). This means scholars of a discipline have read an article carefully and determined that it makes a worthwhile contribution and was researched correctly. This is why instructors prefer you to use peer-reviewed articles -- it guarantees that your sources are good ones.
What is the CRAAP Test? It’s a way to quickly evaluate an article or other source and decide whether it’s something you should use for your research.
We have other databases that'll be particularly helpful in finding articles on topics in computer sciences:
The most efficient way to search ACM Digital Library is to search for your keyword and then narrow down the scope of your results from the initial range of results. For example, if I were looking for articles that mention both human-computer interaction and interfaces, that's exactly the search string I'd use:
Once you have your initial list of results, you can narrow the scope using the tools in the left-hand sidebar. The most useful of these may be the ability to limit your results only to those from certain years:
Once we've found a citation we're interested in reading, we can click into the description of the article to see a summary and to read the article itself:
Note the section for "References." These are very useful for finding articles on similar topics, if this one is especially useful to you. The database will link directly out to references if they're included in ACM:
When your instructor asks you to use peer-reviewed articles, a database is where you'll find them. There are databases for any subject you can think of, and they'll usually let you limit your search (for example only to peer-reviewed articles, or to articles from the past five years).