Dr. Montessori believed that learning is accomplished by the individual himself. The child learns by means of the materials and his own active experience with them. He also learns from others in the environment. Each Montessori classroom has an age range of three years, which allows older children to teach the younger ones and provides the younger ones with a model for future learning. The teacher prepares the environment and gives the child lessons on how the materials are used, guiding the child through a progression of the activities in each curriculum area of the environment. Given the necessary minimum of stimulating interest in the materials, the child begins to manipulate, discover, and learn for himself.