"In education, a core curriculum is a curriculum, or course of study, which is deemed central and usually made mandatory for all students of a school or school system. However, this is not always the case. For example, a school might mandate a music appreciation class, but students may opt out if they take a performing musical class, such as orchestra, band, chorus, etc. Core curricula are often instituted, at the primary and secondary levels, by school boards, Departments of Education, or other administrative agencies charged with overseeing education."
see http://en.wikipedia.org/wiki/Curriculum

See also
"The Common Core State Standards Initiative is a U.S. education initiative that seeks to bring diverse state curricula into alignment with each other by following the principles of standards-based education reform. The initiative is sponsored by the National Governors Association (NGA) and the Council of Chief State School Officers (CCSSO)."
http://en.wikipedia.org/wiki/Common_Core_State_Standards_Initiative

Below you can find more information on the Washington State Learning Standards
http://www.k12.wa.us/curriculuminstruct/ealr_gle.aspx