Below are OER collections containing a variety of Earth Science related course materials (e.g., readings, quizzes, simulations, assignments, and more).

Search OER Commons for Earth Science materials
Link: http://tinyurl.com/zojdpk4

Search MERLOT for Earth Science materials
Link: http://tinyurl.com/jjw7ylo
SEARCH TIP: OER Commons and Merlot allow you to further limit results by sub-disciplines and material type.