The Texas Education Code directs the Texas Education Agency to prepare and distribute a "reorganized curriculum based on operation of schools on a quarter basis," which authorization offers opportunities for curriculum changes in Texas public schools. This guide is designed to provide leadership in curriculum development for school districts as they plan and implement a quarter system. The guide contains both general descriptions of the impact of the quarter system on elementary and secondary schools and specific suggestions for modifying each subject offering and granting credits according to a semester or a quarter unit plan. The publication considers the relation of the quarter system to summer school, compares the impact of the 55-minute period and the 80-minute period, and explains new graduation requirements under the quarter system. Specific school subjects considered include art, business education, drama, driver education, English language arts, foreign languages, health and physical education, industrial arts, mathematics, music, science, social studies, and vocational courses. For each course the document lists grade placement, semester time or credit and course prerequisites required. (Author/DN)