Use each database's thesaurus or subject headings list to identify the best wording for your topic. For example, ERIC uses:
If you are using ERIC to find articles about U.S. contexts, do not add "American" or "United States" or "US" or "USA" to your search. Geography is not indexed in ERIC, and most authors do not use those words in their titles or abstracts. Instead, consider using ERIC's "language" option to limit to English. Also, read each article's abstract careful for information about the location of the study.