In Montessori classrooms, children are grouped according to different planes of development as identified by Dr. Maria Montessori:

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• Primary Classroom - Preschool & Kindergarten (ages 3-6)

• Lower Elementary - grades 1, 2 & 3 (ages 6-9)

• Upper Elementary - grades 4,5 & 6 (ages 9-12)

• Middle School - grades 7 & 8 (ages 13-14)

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Dr. Maria Montessori discovered a brilliant and well-designed solution to the challenge of meeting every child’s needs.  She created, tested, and refined, through observation, auto-didactic (self-teaching) materials to convey specific knowledge to children. As Montessori teachers in mixed-age classrooms, we do not assume all children are learning at the same pace and we respect how a child’s developmental stage directs individual learning using these materials. Our classrooms are filled with these materials that teach a wide range of levels and concepts. Our shelves line the wall and are set up so that at a moments notice a teacher can reach for a material and teach a student or students the concept they need to know. We observe each child and ask ourselves, "What does this child understand? What is the next concept this child needs to learn? In which way does this child learn? What things interest this child so that I can use his/her natural interests and abilities to teach this concept that they need to know?" Once observed, we seek to fulfill their needs through carefully chosen lessons and materials.​ This approach allows children to work at different paces in different areas. A child can move as far ahead as s/he is ready to in one discipline, but can also spend as much time as needed to master a concept s/he finds challenging.