This paper raises a series of questions about the nature of classroom instruction, in general, and about mathematics and reading instruction in the lower elementary school grades, in particular. It focuses on such aspects of the social organization of instruction as (1) the diversity of student populations, (2) the motivating force behind instruction, and (3) the social arrangements through which the on-going monitoring of student work transpires. Overall, the perspective on instruction is based on teachers' commitments to cover the curriculum that the central administration has put in place. The teacher's immediate task is seen to consist of the establishment of forms of instructional organization suitable for conveying the curriculum. The forms of instructional organization are thought of as being responsive to the amount and kinds of student diversity in classes and to what teachers regard as workable arrangements and workable instructional techniques. The workability of arrangements and of techniques is considered to be tied to the activities of monitoring student progress in an on-going fashion to determine when students should move ahead. Reading and mathematics, it is noted, differ in this respect and the difference is related to the fact that monitoring transpires primarily through a written medium in mathematics and an oral medium in reading. (RH)