Beliefs Underlying Open-Space Schools. Proponents of the open classroom stress ac-tive learning and the affective domain. "The primary advantage of open space,M said JohnH. Proctor and Kathryn Smith, "is the increased communication and interaction ofteacher to teacher, teacher to student, and student to student.”" Significant features ofthe open-space concept are the flexibility of grouping and the use of concrete materialsthat appeal to the interests and maturity level of the learners. Whereas many open ele-mentary schools were organized into clusters or teams of a single grade level (e.g., firstgrade), others were nongraded and organized into multiunits.