The use of time in school is undergoing close scrutiny. Over the years, educators have sought to enhance learning time through such reforms as block scheduling and year-round schools. School time can be conceived as an inverted pyramid, in which allocated time (total time in the school day or year) forms the top tier, engaged time (time-on-task) forms the middle tier, and academic learning time forms the bottom tier. Outside-core subjects, such as music, also take up time and are issues of importance to stakeholders. Ineffective ways of managing, preparation for standardized tests, maintaining classroom discipline, and special-day activities (Halloween parties and science fairs) reduce time for teaching. To address these issues, The Responsible Classroom model narrows the scope of the curriculum and lengthens time blocks for indepth learning. Other possibilities include shortening the school year with an added intercession period for low-achieving students, and after-school learning. Most states require a minimum number of school days per academic year, and some use extended-learning programs to add instructional time. Adding time comes with a high cost. Thus, schools should focus on maximizing student engagement and raising the quality of teaching. (Contains 16 references.) (RT)