Openly Available Sources Integrated Search (OASIS) is a search tool that aims to make the discovery of open content easier. OASIS currently searches open content from 71 different sources and contains hundreds of thousands of resources. (OASIS is developed at SUNY Geneseo's Milne Library).
OER include materials and resources other than textbooks: lesson plans, assignments, quizzes/tests, media, syllabi, simulations, and more.