How various methodological decisions may influence studies of the effect of time-on-task on achievement are examined. Subjects were students in grades 2-5 in 18 classes taught by 12 teachers in a rural Maryland school district. All students were pre-tested in February 1978 in reading, language arts, math and social studies using the Comprehensive…

School effectiveness indices (SEIs), based on regressing test performance onto earlier test performance and a socioeconomic status measure, were obtained for eight subject-grade combinations from 485 South Carolina elementary schools. The analysis involved school means based on longitudinally matched student data. Reading and mathematics…