At age 4, boys and girls are taught together in the Pre-Preparatory School. Boys and girls are taught separately from age 7 to 11 in the Preparatory School and also from age 11 to 16 in the Senior School, before joining co-educational classes at 16 for Sixth Form study.

Unlike in single-sex schools, boys and girls at Forest spend time together during break, at lunchtime and after school using the same playgrounds, fields, libraries, social areas, tuck shops, dining hall, buses to school, and engaging in co-educational co-curricular activities such as drama, music, clubs and societies, trips and meetings.