Structural characteristics of classroom activities and student and teacher engagement behaviors were investigated. Observer teams collected data on the structure of activities, student engagement behaviors, and teacher behaviors in arithmetic and reading lessons in six elementary classrooms in a middle class, suburban school district. The structure of academic activity was characterized by six dimensions (group size and teacher presence, supervision, student choice of work group, task, process, and product) jointly referred to as structural configurations. Three general structural configurations were predominant: (1) recitation, characterized by large, teacher-directed group activity; (2) class-task, characterized by various assignments being given to small groups and/or individuals; and (3) multitask, which typically involves independent work of individuals or small, student-directed groups and had the greatest amount of student choice in terms of specific tasks, work partners, processes for completing tasks, and products or outcomes of tasks. Structural changes occurred throughout lessons, but the frequency and extent of the changes varied across teachers. Teachers obtained comparable student engagement levels in different ways. Student engagement appeared to interact with activity structure and teacher engagement. A reliable, cost-effective method was developed. (Author/RL)