Trees start out small and generally maintain their form as they grow progressively bigger and stronger. Children, however, undergo continuous transformation as they develop. Consider the dramatic shifts that occur from a newborn baby to a running toddler, to a nine-year-old engaged in complex group work, to an adolescent navigating the world with increasing independence. They almost seem like different beings at each stage!

Prior to the mid-19th century, human development was largely viewed as linear. A child was considered a "miniature adult" who simply grew older and larger, much like a tree. However, as the study of psychology evolved, researchers began to recognize that humans pass through distinct, sequential stages of growth. This framework became known as Stage Theory.

The Origins of Stage Theory

Stage theories were prominent during the era when Dr. Maria Montessori was developing her educational philosophy. Stage theories break human development down into distinct periods linked to specific age ranges. They propose that certain characteristics, needs, and innate capabilities emerge during each stage to support growth.

Crucially, stage theories emphasize that development is sequential: stages cannot be skipped, as the achievements of one stage form the foundation for the next. Dr. Montessori’s work was part of a broader intellectual conversation that included thinkers such as Jean-Jacques Rousseau, Sigmund Freud, Erik Erikson, Jean Piaget, Lawrence Kohlberg, and later, authors like Gail Sheehy.

Dr. Montessori’s Model: The Four Planes of Development

While Dr. Montessori drew from stage theory, her framework was unique. Rather than focusing solely on cognitive or emotional development, her model was fully holistic, integrating physical, social, emotional, and intellectual growth.

She termed this framework the Planes of Development. Each plane represents a distinct psychological learning period spanning approximately six years:

• First Plane (Ages 0–6): The Absorbent Mind (Infancy and Early Childhood / Toddler & Primary)
• Second Plane (Ages 6–12): The Conscious Mind & Reasoning Mind (Childhood / Lower & Upper Elementary)
• Third Plane (Ages 12–18): Construction of the Social Self (Adolescence)
• Fourth Plane (Ages 18–24): Construction of the Self-Reliant Adult (Maturity)

Dr. Montessori observed that the shifts between these planes are so profound they can be described as metamorphic. The child who enters a new plane undergoes a psychological "rebirth," emerging with entirely new characteristics, interests, and developmental needs.

Designing Environments for Each Stage

Because each plane of development brings distinct physical and psychological needs, education must adapt to support the child at each phase. As Dr. Montessori wrote in The Four Planes of Education:

"The child does not grow in a uniform way day by day, at the same rate. In growth there are crises, somewhat like the metamorphosis of the insects... In fact, it is the child himself who will be the guide of education."

At West Suburban Montessori School, our multi-age classroom environments are purposefully designed to align with these natural developmental planes.

• In our Toddler and Primary environments (First Plane), children learn through tactile exploration, sensory engagement, and practical life activities, utilizing their absorbent minds to effortlessly construct independence and foundational concepts.
• In our Elementary environments (Second Plane), children transition into the period of the reasoning mind. They ask big questions ("Why?" and "How?"), explore moral justice, and thrive on collaborative group work, research, and cosmic education.

A Universal, Positive Approach

Dr. Montessori’s observation of the planes of development offers two key insights that set her approach apart:

1. Universal Applicability: Her observations were not tied to a single culture or time period; they describe universal human characteristics.
2. Focus on Normal Development: Rather than focusing on developmental delays or anomalies, Montessori focused on optimal, natural human development—and constructed a complete educational system, complete with specialized materials and prepared environments, to support it.

Everything we do at WSMS, from the design of our classrooms and selection of materials to the intentional observation practiced by our trained guides, is grounded in this deep respect for the planes of development. We welcome you to come see this for yourself: schedule a tour today.