Use the advanced searching feature if there is one. This will save you some time and limit your search.
Start with broad terms (ex. disease instead of cancer) and then narrow.
As you narrow, think about disciplinary language. Is there something else this topic might be referred to as?
If you still aren't getting good results, try to start with the browsing feature (even if it's very broad). Sometimes the term your searching isn't used but you still know it would be under a broad subject like "humanities" or "writing".
OER Repositories
The following repositories search a variety of open access materials, including OERs, in a variety of disciplines and formats.
This spreadsheet is based on contributions from the open education community organized by CCCOER and Open Education Global to support educators, students, and their families in the transition to online and homebound schooling necessitated during the worldwide COVID-19 pandemic.
Browse purveyors and websites that host openly licensed materials. OER can range from open access textbooks, to lesson plans, to educational videos, to interactive websites, and more.