# What are the Montessori planes of development?

Source: https://www.futurenerds.dev/glossary/planes-of-development
Last updated: 2026-10-25

The planes of development are the four stages of growth Maria Montessori described, each about six years long: birth to 6, 6 to 12, 12 to 18 and 18 to 24. Montessori classrooms are grouped by them. FutureNerds organizes each school's curriculum by age levels that follow the same split.

## The four planes

| Plane | Ages | What the child is working on |
| --- | --- | --- |
| First | 0 to 6 | Building independence, movement, language and the senses |
| Second | 6 to 12 | Reasoning, imagination, and how the world fits together |
| Third | 12 to 18 | Their place in society, and real work with adults |
| Fourth | 18 to 24 | Adult life and a chosen path |

Each plane has two halves of about three years. That is why Montessori classrooms mix three ages: a primary room for 3 to 6, a lower elementary room for 6 to 9, and an upper elementary room for 9 to 12.

## How FutureNerds groups classrooms and lessons

Every curriculum area and classroom in FutureNerds belongs to one age level:

| Age level | Ages | Plane |
| --- | --- | --- |
| Infant/Toddler | 0 to 3 | First, first half |
| Primary | 3 to 6 | First, second half |
| Lower Elementary | 6 to 9 | Second, first half |
| Upper Elementary | 9 to 12 | Second, second half |
| Adolescent | 12 to 15 | Third, first half |

The age level decides which lessons a guide sees in the lesson library and which areas appear on an assessment.

## How to set a classroom's age level in FutureNerds

1. Create or open the classroom.
2. Set its Curriculum Level, such as Primary or Lower Elementary.
3. Check that the curriculum for that level has the areas you teach.
4. Assign the children who belong in that room.

## Related pages

- [Scope and sequence](/glossary/scope-and-sequence)
- [Why the mixed-age classroom works](/blog/mixed-age-classroom)
- [Lesson planning](/product/lesson-planning)
- [Montessori glossary](/glossary)

## Questions and answers

### How many planes of development are there?

Four, each about six years long: 0 to 6, 6 to 12, 12 to 18 and 18 to 24.

### Why do Montessori classrooms mix three ages?

Each plane has two halves of about three years. Grouping children by half-plane lets younger children learn from older ones and older children teach what they know.

### Which age levels does FutureNerds support?

Infant/Toddler, Primary, Lower Elementary, Upper Elementary and Adolescent, each with its own curriculum areas.