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The Third Plane of Development

Ages: Twelve - Eighteen

“If we are among the men of good will who yearn for peace, we must lay the foundation for peace ourselves, by working for the social world of the child.”
     —International Montessori Congress, 

Montessori’s third plane of development, spans ages 12 to 18, and is a transformative period marked by significant physical, emotional, and intellectual changes. Maria Montessori designed her educational approach to cater to the evolving needs of adolescents during this phase, emphasizing independence, self-discovery, and a deep sense of purpose. Here are the hallmarks of Montessori’s third plane of development: 

Identity and Self-Exploration: Adolescents in the third plane are undergoing a period of intense self-discovery. They are eager to explore their own identities, values, and beliefs. Montessori classrooms provide an environment that encourages self-reflection, helping adolescents develop a strong sense of self and understand their place in the world. 

Intellectual Development: During the third plane, adolescents possess a highly developed capacity for abstract thinking. They can understand complex concepts and explore subjects in great depth. Montessori education at this stage focuses on interdisciplinary studies, encouraging students to connect various fields of knowledge and pursue their interests with passion and depth. 

Social Engagement and Collaboration: Adolescents have a deep desire to connect with their peers and the larger community. Montessori environments promote social engagement, encouraging collaboration, teamwork, and a sense of responsibility towards the community. Group projects and community service activities are integrated into the curriculum, fostering a spirit of social responsibility and empathy. 


Exploration of the Adult World: Third plane students are naturally curious about the adult world and aspire to take on adult responsibilities. Montessori education provides opportunities for real-world experiences, such as internships, mentorships, and community projects, allowing adolescents to explore various professions and gain practical life skills. 

Emotional Development and Independence: Montessori’s third plane emphasizes emotional intelligence and independence. Adolescents learn to navigate their emotions, develop resilience, and build healthy relationships. The classroom environment respects their need for independence, allowing them to make choices about their learning paths and take responsibility for their education. 

Ethical and Moral Development: Montessori education during the third plane encourages ethical and moral exploration. Students engage in discussions about social justice, ethics, and global issues, developing a deep understanding of their roles as responsible global citizens. They are encouraged to question societal norms and develop their own moral compass. 

Preparation for Adulthood: Montessori’s third plane prepares adolescents for adulthood by focusing on life skills, time management, and decision-making. Practical life lessons are integrated into the curriculum, empowering students to become self-sufficient and confident as they transition into the next phase of their lives. 

Montessori’s third plane of development is a period of intense self-discovery, intellectual growth, social engagement, and moral exploration. Montessori education recognizes the unique needs of adolescents during this phase, providing a nurturing environment that supports their journey towards becoming responsible, compassionate, and independent adults. 

The Third Plane at Innovation Montessori 

Like the other planes, the third plane is broken into two three-year spans for the purposes of classroom groupings. Secondary 1 includes seventh through ninth grades and Secondary 2 includes tenth through twelfth grades. While Maria Montessori and her son, Mario, clearly defined what Montessori first and second plane classroom and instructional structures, the same is not the case for the third plane. They did state that the focus of this plane must be the social and emotional development of the adolescent and connecting them to purpose. There are a few thought leaders on Montessori Adolescent programs, but you are likely to find different expressions of the third plane depending on the school you visit. Our adolescents must pass all the same courses as their peers in traditional district schools to graduate. It is important to know that as a small school we do not always have all the resources that other larger middle and high schools may have for students in need of remediation.  

Innovation Montessori brings Maria Montessori's educational philosophy to a high school setting.

  • Project Based Learning is an approach to teaching and learning in which students gain knowledge and skills by working for extended periods of time to investigate and respond to an authentic, engaging, and complex question, problem, or challenge.

  • Project Based Learning engages students in learning that is deep, long-lasting and harnesses their critical thinking skills and curiosity.

  • Inquiry Based Learning encourages students to take the lead in their own learning, to grapple with larger guiding questions and with the support of their academic guides unlock answer and knowledge.

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