A review of research on time on task and length of school day or year reveals that time is not the only variable significantly related to student achievement. Research indicates that increasing time in school will not automatically increase student achievement or raise standardized test scores. Other variables such as corrective and immediate feedback, attention to and transfer of prior learning, and active participation of the teacher with students are also important. Quality of time spent in the classroom, then, clearly bears a significant relationship to achievement. (JW)