The Montessori teacher plays the role of unobtrusive director in the classroom as children individually or in small groups engage in self-directed activity. Based on detailed, systematic observation of the children, the teacher seeks to provide an atmosphere of productive calm as children smoothly move along in their learning, alternating between long periods of intense concentration interspersed with brief moments of recovery/reorganization (Oppenheimer, 1999). The teacher's goal is to help and encourage the children, allowing them to develop confidence and inner discipline so that there is less and less need to intervene as the child develops. Interrupting children when engaged in purposeful activity interferes with their momentum, interest, and inner workings of thought (Greenwald, 1999). During the early childhood years, the teacher brings the young child into close contact with reality through sensory investigation and practical activity and then relies on the child's unfolding inner program of curiosities and sensitivities to ensure that the child will learn what he or she needs. With the younger students at each level, the teacher is more active, demonstrating the use of materials and presenting activities based on an assessment of the child's requirements.