A model is presented for studying how schools provide instruction to students. A major function of the National Center for Education Statistics is to collect data for understanding and improving how schools provide instruction. The model describes school factors (characteristics, staffing, organization, policy, and student evaluation); classroom operating conditions (instructional quality time on task, and social and learning environment); student inputs (individual needs, abilities, and interests); peer group and community factors; and student outcomes (academic skills, personal development, and attachment to school and good behavior). A number of guidelines for research design are discussed: (1) the school or classroom, not the student, should be the unit of analysis; (2) the sampling unit should be the school and classrooms, and a wide variety should be included; (3) school policy and classroom practices need to be measured appropriately; (4) descriptive data should be collected before causal conclusions can be made; and (5) the impact of school-level treatments on students should be measured and continued as students move on. Fourteen sample questionnaire items are included, as well as a five-page reference list. (GDC)