OER stand for Open Educational Resources. OER materials can be used, remixed, and distributed at no cost because the original creator maintains few of their rights as owners. Many OER materials have a Creative Commons License.
The term OER can refer to any educational material that is freely available, from textbooks, syllabi, full courses, activities, worksheets, etc.
OER can be created by anyone interested in having freely available information on a subject. Many OER providers are associated with a university, or educational company. Before selecting OER material to use in a classroom, research the provider to determine if they are an appropriate authority on the topic.
While OER is still fairly new, studies so far indicate that students in courses using OER material perform as well or better than courses that use traditional paid material or textbooks. Here are a few studies on classrooms using OER material and student success.
Colvard, N. B., Watson, C. E., & Park, H. (2018). The impact of open educational resources on various student success metrics. International Journal of Teaching and Learning in Higher Education, 30(2), 262–276.