Answer:
Studies at both the K-12 and higher education levels show that students who use OER do as well, and often better, than their peers using traditional resources. Also, many OER are developed through rigorous peer review and production processes that mirror traditional materials. However, it is important to note that being open or closed does not inherently affect the quality of a resource.
Being open does enable educators to use the resource more effectively, which can lead to better outcomes. For example, OER can be updated, tailored and improved locally to fit the needs of students, and it also eliminates cost as a barrier for students to access their materials.