My son's preschool divided the classroom into activity centers, such as art, writing, reading (library), social studies, science, computers, music, "real" play (dress-up/pretend), with plenty of games, activities, and materials available to support the child's interaction with each other. Two children at a time could participate in an activity center to promote sharing and one-on-one interaction.
Large group activities included circle time, outdoor/indoor play, story hour (local children's librarian), and meals aided socialization. These were directed by the classroom teacher, unless free play was allowed.
Small group activities like crafts, letter/number practice, and theme-based small group activities provided more direct instruction from the classroom teacher.
Naptime was an individual activity (each child on a separate cot).
Each week had a theme and each day focused in on a topic related to that theme.
The children learned the routines and rules quickly. The teacher guided the activities as necessary and the classroom aide assisted with instruction and with classroom management.