The proportion of time that elementary school teachers use to teach core academic subjects (English/reading/language arts, mathematics, social studies, science) is an important aspect of instruction. Spending a large proportion of time teaching core curriculum subjects may be important not only in terms of school quality, but also in terms of teacher satisfaction. This report compares the amount of time spent teaching the four basic subjects to the amount of time students spend in school each week. It compares various school and student variables, such as control of school, urbanicity, school size, percentage of minority students, and percentage of students eligible for free lunch, as well as other classroom and teacher variables. Data come from the Schools and Staffing Survey for years 1987-88 to 1993-94. Given the heterogeneity of schools in the United States, remarkably few differences were found in the percentage of school time teachers in the first four grades spent on the core subjects. Public school teachers spent about 68% of their time, or almost 22 hours each week, on core curriculum, and private school elementary teachers spent about 58% of their time. The percentage of time spent on core subjects changed relatively little from 1987 to 1994. However, teachers spent more time on out-of-classroom activities in 1993-94, a finding that may explain how teachers balance the pressures of instructional time and time for additional responsibilities. Three appendixes contain tables concerning time allocation, standard errors for those tables, and technical notes for the analysis. (Contains 5 tables, 22 appendix tables, 4 figures, and 17 references.) (SLD)