Core curricula tend to consume a block of time consisting of two to three periodsof the school day. The remaining periods are devoted to specialized interests of students."Block-time classes” is a term sometimes equated with "core.” However, block-timeclasses may or may not be core classes?5Reporting in 1958 on a survey of block-time classes and core programs in juniorhigh schools, Grace S. Wright listed four types of programs in block-time classes asfollows: