The discussion of OER often does not clearly distinguish various levels of granularity: OER can
comprise a wide range of artifacts from a single photo to a complete instructional set for a
semester or school year comprising of a text and workbook with an accompanying interactive
website, audiovisual material or training units. Weller (2011) distinguishes little OERs,
individually produced low-cost resources, and big institutionally generated OERs. The following
table shows the most typical use cases discussed as OERs.