How consistent are human judgments of whether an open resource is educational material?

Michael C. Harris James A. Thom Falk Scholer How consistent are human judgments of whether an open resource is educational material? 9-18 2010 ADC http://portal.acm.org/citation.cfm?id=1862247&CFID=17470975&CFTOKEN=71845406 conf/adc/2010 db/conf/adc/adc2010.html#HarrisTS10