Why Are Montessori Classrooms Mixed-Age?

One of the most obvious differences between traditional public school and Montessori schools are the multi-age learning environments. This practice is so important to the Montessori method, that a school must have the multi-year age span to call itself a Montessori school!

In a mixed-age classroom children stay with the same teacher for three or more years. This allows the teacher to plan around a three year cycle and give the child more time to practice and master material. Older children have the opportunity to learn leadership, and younger students have more mature peers to look up to as role models.

This post focusses on the elementary child, but these principles apply to older and younger children as well.

What are the benefits of a multi-age classroom?

Montessori classrooms are mixed-age because experience and over a century of practice has shown that this is what’s best for the development of the child.

Children Can Work at Their Own Pace

The biggest benefit of a multi-age classroom is that children can work at their own pace, and they’re not held to the same speed as everyone else in the class. 

No two children are the same. Children with the same birth year may be approximately at the same level, but no two children are going to be at the same point in their learning development at the same time, and proceed at the same pace. A pace that is often too slow or too fast, because the classroom caters to the “average” student. 

In an age-segregated classroom, the individual differences of children are ignored, not from malice, but in the name of efficiency. Children receive group instruction, one-size-fits-all assignments, and rigid timetables for completing work and moving onto the next level of work. This method is standard in most schools, and makes the job of the teacher much easier.

For the child that is advanced, this pace artificially constrains growth, they must sit idly and wait for the rest of the class before moving on. For the child that needs more practice, this pace is cruel. They are expected to perform at an unhealthy accelerated pace, and are ultimately almost always left behind.

The amount of practice a child needs also varies with different subject areas. A given student may be very mathematically inclined, but struggle with language arts. Moving them up or down a “grade level” to match their abilities would serve them in one domain and hinder them in another.

How does a mixed age classroom fix this problem? The mixed age classroom, by necessity, groups children by ability and gives individual instruction. I could not stand at the from of my class and give a the same math lesson to a group of six-, seven-, and eight-year-olds. I must give many individual lessons instead.

In my own classrooms, I’ve had struggling readers who needed more practice with younger peers, and I’ve had advanced mathematicians who were excelling at mathwork years above their same-age peers. In a Montessori classroom, this isn’t a problem! When I set out to teach a lesson, I invite every child that is ready, regardless of their birthday.

Mastery Fixed, Time Variable

In a traditional classroom, the amount of time given to a topic is standardized, every child will get the exact same amount of practice and instructional time to master a topic. At the end of the allotted time, their mastery will be measured and they will be given a grade that represents that level of mastery, an “A, B, or C” letter grade. Regardless of their level of mastery, the next lesson will be given. Mastery is variable, time is fixed.

In a Montessori classroom, mastery of core knowledge is fixed, but the amount of time that may take will vary from child to child. This is one reason that there are no letter grades in our classrooms, all children will achieve an “A.” Time is variable, some will achieve it in a few days, some will achieve it in a few weeks, but they won’t move on until they have mastered the content. 

Montessori report card

Fosters a Growth Mindset

In a traditional classroom, you only compare yourself to your same-age peers in the same classroom. You know who the “smart kids” are, and you know where you fit in that ranking. This promotes a fixed-mindset where children think their abilities are innate and unchanging. Unhealthy competition and conformity are implicitly encouraged.

Imagine you are a young six year old and you’re working with the stamp game (basic arithmetic), across the room another child who is a mere 3 years older than you is working on squaring and cubing work. You can see the path to this advanced work and it seems achievable. Indirectly, the older child is a role model and encouraging a growth mindset for the younger.

Emulates the “Real World”

Grouping people by age is unnatural, and ignores differences in ability and interest. As an adult I have worked with people many years older and younger than myself. We found ways to work together and solve problems based on our shared abilities, not our birthday. This led to rich diversity in approach, philosophy and experience. Everyone has something unique to bring to the table, and this fact is no different for children.

Montessori classrooms encourage cooperation and collaboration between students. Older students model classroom norms to younger students and younger students look up to their older counterparts. In our classrooms, children will work with classmates who have more expertise, and with others who have less. In a multi-age classroom, there is a wide array of skill levels across the curriculum and children will naturally mentor each other and learn from each other, because they want each other to succeed.

This is true preparation for life where as an adult, they will work with people at different ability levels.

The Drawbacks of a Mixed-Age Classroom

I have a strong bias that mixed-age classrooms are overwhelmingly positive for children, but it is wise to clearly think about some of the tradeoffs that occur whenever you have alternatives.

The main tradeoffs I see of a mixed-age classroom are that children will necessarily learn different material and that lesson planning is significantly harder for the teacher, especially if she is not specially trained or is not in a Montessori environment.

Children Will Learn Different Material

I want to emphasize first that different does not mean academics are less rigorous. The struggling child is not held to a lesser, “modified” standard, they are still held to a mastery standard. But time is finite, so spending extra weeks to master core content means they might not receive as many advanced lessons and they may not receive “bonus” lessons.

But what good are advanced lessons if the child hasn’t mastered the core content?

Advanced students may receive lessons that are beyond what is strictly required because they love the work and have a thirst for knowledge. The scope and sequence has a “main strand” of necessary, non-negotiable content that every child will receive, but it also includes many extra strands of work that are optional specifically for these advanced students. For example doing arithmetic in binary or hexadecimal is not strictly necessary content, but if a child is particularly inclined toward math work, they will be delighted in the extra challenge.

A drawback is that if a student progresses in a particular area of the class well beyond their peers, they may have fewer opportunities to do collaborative work. Collaborative work is very motivating and enjoyable to the elementary child and it is encouraged. But peer work is not encouraged at the expense of intellectual development. 

What lesson would we teach our children if we held them back just so that they could “fit in” with classmates?

Both scenarios, covering fewer advanced lessons and covering extra advanced lessons might make a student stick out in a conventional classroom. But in a Montessori classroom, all children are completing different work at any given time already, so it’s not obvious. Children are observant and may still notice, so my explanation to the children is that “everyone gets what they need,” and they understand that.

Planning Curriculum Is Harder for the Teacher

Multi-age classrooms are difficult to implement; they are designed for the child, not the adult. Because there are no whole group lessons, educators must plan an individual curriculum plan for each child, ensuring that each subject area is sufficiently challenging and that the child is completing enough practice to master the material. They must also find ways for deeper exploration into a topic if a child is interested in Big Work and find ways to scaffold if a child needs the lesson modified. 

Educators must be specially trained in the entire scope and sequence for the entire age range that they teach in every subject area. It is even preferable if the guide has some professional development in the ages just before and just after their area of expertise. This training is difficult and takes many years to truly master.

If you are a teacher who is not in a Montessori classroom, with its 3-hour uninterrupted work period and didactic materials, this may not even be possible. The time and effort required to give each child an individual lesson, check in on practice and assess for understanding every day keeps the teacher quite occupied!

I personally find this part of my job to be the most satisfying (it’s a constant puzzle to solve!) but it is undoubtedly difficult.

But What if My Struggling Child Never Progresses?

Let’s say a child was introduced to the Checkerboard and they aren’t connecting with the material. This material helps children practice multi-digit multiplication into the millions. As the teacher, I have a few options to help:

  1. I can re-present the lesson. Sometimes a child will need to see something done multiple times before they are ready for independent practice. I’m happy to sit with the child while they practice to find out exactly where the confusion is.
  2. The child could work with someone else, perhaps an older student, who does understand the material. In my own experience, having a peer explain things can often clear up confusion, and makes the work more enjoyable.
  3. I can teach the concept on a different material. The Montessori Materials are a scaffold, they are a way to make abstract concepts concrete, they are not an end in themselves. I could use the Large Bead Frame, a material that looks like an abacus, to teach the same idea in a different way and then we could return to the Checkerboard at a later time.
  4. We can step away for a bit. Perhaps the child wasn’t developmentally ready for that lesson. We can practice related math concepts, maybe skip counting or squaring with the bead chains, and then return to this particular lesson in a couple weeks.

The important take-away is that children will not be “left behind,” and a Montessori classroom offers a lot of flexibility to meet the individual needs of children. Time variable, mastery fixed.


Do you have an experience from school or college where you weren’t progressing at the same speed as the rest of the class? Did any particular part of this post resonate with you? Leave a comment below to start a conversation.

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